Slide surface construction and process for producing the same

ABSTRACT

A slide surface construction of a slide bearing is formed of an aggregate of two different metal crystals. The sliding condition of a first region of the slide bearing is more severe than that of a second region. The (2hhh) oriented metal crystals having a body-centered cubic structure with their (2hhh) planes (by Miller indices) oriented toward a slide surface exist in the first region. The content S 2hhh  of the (2hhh) oriented metal crystals is set in a range of S 2hhh  ≧20%. These crystals have a high hardness and are in the form of fish-like metal crystals in the slide surface and hence, an aggregate of these metal crystals has a good oil retention. The (hhh) oriented metal crystals having a body-centered cubic structure with their (hhh) planes (by Miller indices) oriented toward a slide surface exist in the second region. The content S hhh  of the (hhh) oriented metal crystals is set in a range of S hhh  ≧40%. These crystals are in the form of hexagonal pyramid-shaped metal crystals and hence, an aggregate of these metal crystals has a good oil retention. Thus, it is possible for the two regions with different sliding conditions to exhibit an excellent sliding characteristic.

This is a Continuation-In-Part of Ser. No. 08/236,901, filed Apr. 29,1994, issued as U.S. Pat. No. 5,503,942 on Apr. 2, 1996.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a slide surface construction andparticularly, to a slide surface construction formed of an aggregate ofmetal crystals and a process for producing the same.

2. Description of the Related Art

There are conventionally known slide surface constructions. Typicalexamples of such known slide surface constructions are: 1) a Pb alloyplated layer provided on the inner peripheral surface of a rolled-steelback plate of a slide bearing for an internal combustion engine, whichis opposed to a rotary shaft, for the purpose of enhancing the seizureresistance; 2) various plated layers provided on an inner peripheralsurface of a cylinder sleeve made of a cast iron in a combination of apiston made of an aluminum alloy and such cylinder sleeve in an internalcombustion engine for the purpose of enhancing the slide characteristic;and 3) an Fe-plated layer provided on outer peripheral surfaces of aland portion and a skirt portion of a piston body made of an aluminumalloy in a piston for an internal combustion engine for purpose ofenhancing the wear resistance.

However, the above known slide surface constructions suffer from aproblem that under existing circumstances where speed and output of theinternal combustion engine have tended to increase, the known slidesurface construction is not sufficient in oil retaining property,namely, oil retention and poor in seizure resistance due to a relativelysmooth slide surface thereof.

There is also a conventionally known slide surface construction which isformed on an engagement surface of a gear in a gearing device byroughening the engagement surface by machining or the like, and thenapplying a solid lubricating agent such as molybdenum disulfide,graphite and the like, or a semi-solid lubricating agent such as greaseonto the roughened engagement surface, so that latter retains thelubricating agent.

However, the known engagement surface is simple in view ofmicrostructure and has a problem that it is low in solid lubricatingagent retention and the like and, as a result, is poor in seizureresistance under a high load condition.

Therefore, the present assignee has previously developed a slide surfaceconstruction which is formed on an inner peripheral surface of a backingplate, an inner peripheral surface of a cylinder sleeve, an outerperipheral surface of a piston body, an engagement surface of a gear andthe like, and which includes a large number of pyramid-shaped metalcrystals in the slide surface thereof (see Japanese Patent ApplicationLaid-open No.174089/94).

If the slide surface construction is formed in the above manner,adjacent pyramid-shaped metal crystals assume mutually biting states andhence, the slide surface takes on an intricate aspect comprising a largenumber of fine crests, a large number of fine valleys formed between thecrests, and a large number of swamps formed due to the mutual biting ofthe crests. Therefore, the slide surface construction is improved in oilretention and in solid lubricating agent retention and the like andthus, has an enhanced seizure resistance.

In the above-described slide bearing, however, the following situationhas been encountered: when two regions suitable under different slidingconditions are produced in the slide surface construction, even if oneof the two regions exhibits a good sliding characteristic under a severesliding environment, it cannot be expected that the other regionexhibits such a good sliding characteristic, because the slidecharacteristic of the slide surface construction is substantiallyconstant over the entire region thereof.

As for the gearing device, it has been ascertained that in order toaccommodate the severe sliding environment, for example, where a suddenand excessively large variation in load occurs in the gear, it isnecessary to further enhance the solid lubricating agent retention ofthe slide surface construction.

As for the cylinder sleeve, it has been ascertained that when theviscosity of the oil is high, for example, at a lower temperature, theflow of the oil lacks a smoothness, resulting in a relatively highdynamic friction coefficient μ and for this reason, the friction losstends to be increased.

Further, as for the piston, it has been also ascertained that in orderto accommodate the severe sliding environment, it is necessary tofurther enhance the oil retention of the slide surface construction toreduce the solid contact to the utmost, thereby further enhancing theseizure resistance, and to reduce the dynamic friction coefficient μ tofurther enhance the wear resistance.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a slide surfaceconstruction of the above-described type, wherein it is possible for tworegions suitable under different sliding conditions to exhibit excellentsliding characteristics, respectively.

To achieve the above object, according to the present invention, thereis provided a slide surface construction formed of an aggregate of metalcrystals, comprising first and second regions suitable under differentsliding conditions, the first region including (2hhh) oriented metalcrystals existing therein, which have a body-centered cubic structurewith their (2hhh) planes (by Miller indices) oriented toward a slidesurface, the content S_(2hhh) of the (2hhh) oriented metal crystalsbeing set in a range of 20%≦S_(2hhh) ≦100%, and the second regionincluding (hhh) oriented metal crystals existing therein, which have abody-centered cubic structure with their (hhh) planes (by Millerindices) oriented toward a slide surface, the content S_(hhh) of the(hhh) oriented metal crystals being set in a range of 40%≦S_(hhh) ≦100%.

In the first region, the (2hhh) oriented metal crystals are grown into acolumnar shape, with their tip ends being formed of fish-shaped metalcrystals such as sardine-shaped metal crystals in the slide surface. Ifthe content of the (2hhh) oriented metal crystals is set in theabove-described range, the slide surface takes on a very intricateaspect due to the large number of fish-shaped metal crystals existing inthe slide surface and therefore, it has a good oil retention. Moreover,the (2hhh) planes of the (2hhh) oriented metal crystals form a secondaryslide surface and hence, they have a high hardness and a high strength.

The second region is most suitable for use in a site of a severe slidingcondition.

On the other hand, in the second region, the (hhh) oriented metalcrystals are grown into a columnar shape, with their tip ends beingformed of hexagonal or trigonal pyramid-shaped metal crystals in theslide surface. If the content of the (hhh) oriented metal crystals isset in the above-described range, the slide surface takes on a veryintricate aspect due to the large number of hexagonal or trigonalpyramid-shaped metal crystals existing in the slide surface andtherefore, it has a good oil retention. However, the (hhh) orientedmetal crystals has a low hardness, as compared with the (2hhh) orientedmetal crystals.

The first region is most suitable for use in a site of a slidingcondition in which a seizure resistance is preferentially required andwhich is more moderate than that of the first region.

In this way, according to the present invention, it is possible toprovide a slide surface construction in which the two region suitableunder different sliding conditions can exhibit excellent slidecharacteristics, respectively by the fact that the slide surfaceconstruction has a specified structure as described above.

However, if the content S_(2hhh) is lower than 20%, or if the contentS_(hhh) is lower than 40%, the above-described function and effectcannot be provided.

It is another object of the present invention to provide a slide surfaceconstruction of the above-described type, which has a further enhanceretention to the slide lubricating agent and the like.

To achieve the above object, according to the present invention, thereis provided a slide surface construction formed of an aggregate of metalcrystals, wherein the area rate A of pyramid-shaped metal crystals in aslide surface is in a range of 40%≦A≦100%, at least some of thepyramid-shaped metal crystals being heteromorphic pyramid-shaped metalcrystals having at least one notched recess in at least one ridgelinesection, the pseudo-area rate B of the heteromorphic pyramid-shapedmetal crystals in the slide surface being in a range of 20%≦B≦100%.

If the area rate A of pyramid-shaped metal crystals in a slide surfaceis set in the above-described range, the adjacent pyramid-shaped metalcrystals assume mutually biting states and hence, the slide surfacetakes on an intricate aspect comprising a large number of fine crests, alarge number of fine valleys formed between the crests, and a largenumber of fine swamps formed due to the mutual biting of the crests.Thus, the slide surface construction exhibits a good retention to theslide and semi-solid lubricating agents. Moreover, since the pseudo-arearate B of the different pyramid-shaped metal crystals is set in theabove-described range, the notched recess in the metal crystal exhibitsan anchoring effect to the solid and semi-solid lubricating agents,thereby doubling the retention.

In the slide surface construction, even if it is placed in a severesliding environment, the lubricant retention of the slide surfaceconstruction is maintained at a high degree under lubrication, while thedispersion of a sliding load is provided by the large number of finepyramid-shaped metal crystals under non-lubrication. Thus, the slidesurface construction exhibits an excellent seizure resistance both underlubrication and under non-lubrication.

In this way, according to the present invention, it is possible toprovide a slide surface construction which has a good retention of thesolid and semi-solid lubricating agents and exhibits an excellentsliding characteristic under a severe sliding environment, for example,where a sudden and excessively large variation in load occurs, by thefact that the slide surface construction has a specified structure asdescribed above.

However, if the area rate A of the pyramid-shaped metal crystals islower than 40%, the slide surface tends to be simplified and hence, sucha range is not desirable. If the pseudo-area rate B of the differentpyramid-shaped metal crystals is lower than 20%, the anchoring effectcannot be expected.

It is a further object of the present invention to provide a process forproducing a slide surface construction of the above-described type,which is capable of producing a slide surface construction having afurther enhanced retention to the solid lubricating agent and the like.

To achieve the above object, according to the present invention, thereis provided a process for producing a slide surface construction formedof an aggregate of metal crystals by an electrolytic plating treatmentutilizing a pulse current process, wherein the electrolytic platingtreatment is divided into a plurality of steps, an energization stoppingstep being interposed between a step of the last time and a step of thecurrent time, the time T₂ required for the energization stopping stepand the minimum electric current maintaining time T₁ in the step of thelast time being in a relationship of T₂ ≧100 T₁, and the average cathodeelectric-current density CD₂ in the step of the current time and theaverage cathode electric-current density CD₁ in the step of the lasttime being in a relationship of CD₂ ≧1.2 CD₁.

With the above producing process, a slide surface construction includingpyramid-shaped metal crystals and different pyramid-shaped metalcrystals in the slide surface can be easily mass-produced. However, ifT₂ <100 T₁, or if CD₂ <1.2 CD₁, the pseudo-area rate. B of the differentpyramid-shaped metal crystals is lower than 20%.

Further, it is another object of the present invention to provide aslide surface construction of the above-described type, wherein thefriction loss can be reduced even when the oil has a high density.

To achieve the above object, according to the present invention, thereis provided a slide surface construction formed of an aggregate of metalcrystals, wherein the area rate A of rounded pyramid-shaped metalcrystals in a slide surface is in a range of 40%≦A≦100%, each of therounded pyramid-shaped metal crystals having a ridgeline which assumes aconvex arcuate shape, a slope-correspondence area (which means an areacorresponding to a slope) being defined between the adjacent ridgelinesand comprising two band-like regions each of which is one of slopesforming each ridgeline, and a V groove-like region connected to the twoband-like regions, the opening width of the V groove-like region beinggradually reduced from a skirt portion toward an apex.

If the area rate A of the rounded pyramid-shaped metal crystals is setin such range, the adjacent rounded pyramid-shaped metal crystalsassumes mutually biting states. Therefore, the slide surface takes on anintricate aspect comprising a large number of fine crests, a largenumber of fine valleys formed between the crests, and a large number offine swamps formed due to the mutual biting of the crests.

In this case, if each of the ridgelines of the pyramid-shaped metalcrystal is rectilinear and the apex of the pyramid-shaped metal crystalis pointed, and if the slope-correspondence area between the adjacentridgelines is formed into a relatively deep V shape such that theopening width is gradually reduced from the skirt potion toward theapex, namely, if the pyramid-shaped metal crystal is angular, thefollowing problem is encountered: when the viscosity of an oil is highat a low temperature, the flow of the oil lacks a smoothness, becausethe angular pyramid-shaped metal crystals perform an occluding effect.

In contrast, if the rounded pyramid-shaped metal crystals as describedabove exist in the slide surface, the flow resistance of the oil havinga high viscosity is reduced on the slide surface and therefore, it ispossible for the oil to flow smoothly. Thus, it is possible to reducethe shear resistance of an oil film formed on the slide surface reducethe friction loss.

Since the slide surface takes on the intricate aspect, as describedabove, the slide surface construction has a good oil retention,substantially irrespective of the viscosity of the oil. Thus, the slidesurface construction exhibits an excellent seizure resistance, even ifit is placed in a severe sliding environment. On the other hand, evenunder non-lubrication, the dispersion of a sliding load is provided bythe large number of fine rounded pyramid-shaped metal crystals andhence, the seizure resistance of the slide surface construction isrelatively good.

If the area rate A of the rounded pyramid-shaped metal crystals is lowerthan 40%, the slide surface tends to be simplified and hence, such anarea rate A lower than 40% is undesirable.

It is a yet further object of the present invention to provide a slidesurface construction of the above-described type, wherein the seizureresistance can be further enhanced and the dynamic friction coefficientμ can be lowered to further enhance the wear resistance by furtherenhancing the oil retention to reduce the solid contact to the utmost.

To achieve the above object, according to the present invention, thereis provided a slide surface construction formed of an aggregate of metalcrystals, comprising a large number of truncated hexagonalpyramid-shaped metal crystals in a slide surface, the area rate A of thetruncated hexagonal pyramid-shaped metal crystals being in a range of40%≦A≦100%, a top face of each of the truncated hexagonal pyramid-shapedmetal crystals comprising a plurality of flat face portions, with a stepprovided between adjacent ones of the flat face portions.

If the area rate A of the truncated hexagonal pyramidshaped metalcrystals in the slide surface is set in such range, a complicated valleyextending at random is defined by the adjacent truncated hexagonalpyramid-shaped metal crystals and therefore, the slide surface takes onan intricate aspect. Moreover, the intricateness is doubled by the factthat the top face of each truncated hexagonal pyramid-shaped metalcrystal comprises the plurality of flat face portions and the step isprovided between the adjacent flat face portions. As a result, the flowresistance of the oil on the slide surface is remarkably increased.

Thus, it is possible to remarkably enhance the oil retention of theslide surface construction and hence, even in a severe slidingenvironment, the solid contact can be reduced to the utmost, causing theslide surface construction to exhibit an excellent seizure resistance.In addition, since the top face has the flat face portions, the dynamicfriction coefficient μ can be lowered, causing the slide surfaceconstruction to exhibit an excellent wear resistance in the severesliding environment.

Yet further, it is an object of the present invention to provide aprocess for producing a slide surface construction of theabove-described type, by which the slide surface construction can bemass-produced.

To achieve the above object, according to the present invention, thereis provided a process for producing a slide surface construction,comprising: a step for forming a deposit layer including a large numberof pyramid-shaped metal crystals in a surface serving as a slide surfaceand having an area rate A of the pyramid-shaped metal crystals in thesurface in a range of 40%≦A≦100%; a step for subjecting a surface of thedeposit layer to a polishing to form the pyramid-shaped metal crystalsinto truncated pyramid-shaped metal crystals; and a step for subjectingthe surface of the polished deposit layer to an etching to divide a topface of each of the truncated pyramid-shaped metal crystals into aplurality of flat face portions and to provide a step between theadjacent flat face portions.

With the above producing process, a slide surface construction asdescribed above can be mass-produced.

The above and other objects, features and advantages of the followingdetailed description of preferred embodiments taken in conjunction withthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a connecting rod including a slide bearing;

FIG. 2 is an enlarged view of a portion indicated by the arrow 2 in FIG.1;

FIG. 3 is a developed view of a semi-annular half of the slide bearing;

FIG. 4 is an enlarged sectional view taken along a line 4--4 in FIG. 3;

FIG. 5 is a perspective view showing a body-centered cubic (bcc)structure and its (hhh) plane and (2hhh) plane;

FIG. 6 is a plan view of a trigonal pyramid-shaped metal crystal;

FIG. 7 is a diagram showing the inclination of the (2hhh) plane in thebody-centered cubic structure;

FIG. 8 is a diagram showing the inclination of the (hhh) plane in thebody-centered cubic structure;

FIG. 9 is a graph of a waveform of an output from a power source forelectrolytic plating;

FIG. 10 is a diagram illustrating how X-ray is applied to the slidesurface;

FIG. 11 is an X-ray diffraction pattern for an example 1a of a firstregion of a slide surface;

FIG. 12 is an X-ray diffraction pattern for an example 4a of the firstregion of a slide surface;

FIG. 13 is a photomicrograph showing the crystal structure of the slidesurface of the example 1a;

FIG. 14 is a photomicrograph showing the crystal structure of the slidesurface of the example 4a;

FIG. 15 is a photomicrograph showing the crystal structure of the slidesurface of an example 8a;

FIG. 16 is a graph illustrating the relationship between the contentS₂₁₁ of {211} oriented Fe crystals and the seizure generating load;

FIG. 17 is a graph illustrating the relationship between the contentS₂₁₁ of {211} oriented Fe crystals and the wear resistance;

FIG. 18 is an X-ray diffraction pattern for an example 1b of a secondregion of a slide surface;

FIG. 19 is an X-ray diffraction pattern for an example 5b of the secondregion of a slide surface;

FIG. 20 is a photomicrograph showing the crystal structure of the slidesurface of the example 1b;

FIG. 21 is a photomicrograph showing the crystal structure of the slidesurface of the example 5b;

FIG. 22 is a graph illustrating the relationship between the contentS₂₂₂ of {222} oriented Fe crystals and the seizure generating load;

FIG. 23A is a front view of a piston;

FIG. 23B is a view take along an arrow 23B in FIG. 23A;

FIG. 24 is a graph illustrating the relationship between the contentS₂₁₁ of {211} oriented Fe crystals and the seizure generating load;

FIG. 25 is a sectional view of an essential portion of a gearing device;

FIG. 26 is an enlarged view of a portion indicated by an arrow 26 inFIG. 25;

FIG. 27 is a view taken in the direction of an arrow 27 in FIG. 26;

FIG. 28A is a perspective view of a heteromorphic hexagonalpyramid-shaped metal crystal;

FIG. 28B is a perspective view of a normal hexagonal pyramid-shapedmetal crystal;

FIG. 29 is a graph of a waveform of an output from an electrolyticplating power source;

FIG. 30 is an X-ray diffraction pattern for an example 1;

FIG. 31 is an X-ray diffraction pattern for an example 11;

FIG. 32 is an X-ray diffraction pattern for an example 15;

FIG. 33A is a photomicrograph showing the crystal structure of the slidesurface of the example 1;

FIG. 33B is a photomicrograph showing the crystal structure of avertical section of the example 1;

FIG. 33C is an enlarged photomicrograph of an essential portion shown inFIG. 33B;

FIG. 34 is a photomicrograph showing the crystal structure of the slidesurface of the example 11;

FIG. 35 is a photomicrograph showing the crystal structure of the slidesurface of the example 15;

FIG. 36 is a graph illustrating the relationship between the area rate Aof hexagonal pyramid-shaped Fe crystals and the seizure generating load;

FIG. 37 is a graph illustrating the relationship between the area rate Aof hexagonal pyramid-shaped Fe crystals and the dynamic frictioncoefficient μ;

FIG. 38 is a graph illustrating the relationship between the averagecathode current density in a second step and the pseudo-area rate B ofheteromorphic hexagonal pyramid-shaped Fe crystals;

FIG. 39 is a partial vertical sectional view of an essential portion ofa cylinder block including a piston;

FIG. 40 an enlarged view of a portion indicated by an arrow 40 in FIG.39;

FIG. 41 is a view taken in the direction of the arrow 41 in FIG. 40;

FIG. 42A is a perspective view of a rounded hexagonal pyramid-shapedmetal crystal;

FIG. 42B is a plan view of the rounded hexagonal pyramid-shaped metalcrystal;

FIG. 43 is a perspective view of an angular hexagonal pyramid-shapedmetal crystal;

FIG. 44 is a broken-away perspective view of a round bar having a slidesurface construction;

FIG. 45 is an X-ray diffraction pattern for an example 1 of the slidesurface construction;

FIG. 46 is an X-ray diffraction pattern for an example 4 of the slidesurface construction;

FIG. 47 is an X-ray diffraction pattern for an example 8 of the slidesurface construction;

FIG. 48A is a photomicrograph showing the crystal structure of the slidesurface of the example 1;

FIG. 48B is an enlarged photomicrograph taken from FIG. 48A;

FIG. 48C is an enlarged photomicrograph taken from FIG. 48B;

FIG. 49 is a photomicrograph showing the crystal structure of the slidesurface of an example 3;

FIG. 50 is a photomicrograph showing the crystal structure of the slidesurface of an example 4;

FIG. 51 is a photomicrograph showing the crystal structure of the slidesurface of an example 8;

FIG. 52 is a view for illustrating how a dynamic friction coefficient μis measured;

FIG. 53 is a graph illustrating the relationship between the area rate Aof rounded and angular hexagonal pyramid-shaped Fe crystals and thedynamic friction coefficient μ;

FIG. 54 is a graph illustrating the seizure generating loads for theexamples 1 to 8;

FIG. 55 is a front view of an essential portion of a piston with aportion broken away;

FIG. 56 is an enlarged sectional view taken along a line 56--56 in FIG.55;

FIG. 57 is a view taken in the direction of the arrow 57 in FIG. 56;

FIG. 58A is a plan view of truncated hexagonal pyramid-shaped metalcrystals;

FIG. 58B is an enlarged sectional view taken along a line 58B--58B inFIG. 58A;

FIG. 59 is a sectional view similar to FIG. 56, but showing a depositlayer;

FIG. 60 is a view taken in the direction of the arrow 60 in FIG. 59;

FIG. 61 is a side view similar to FIG. 57, but showing a deposit layerafter being polished;

FIG. 62 is an X-ray diffraction pattern for an example 1a of the depositlayer;

FIG. 63 is a photomicrograph showing the crystal structure of a surfaceof the example 1a of the deposit layer;

FIG. 64 is a photomicrograph showing the crystal structure of a surfaceof an example 3a of the deposit layer;

FIG. 65 is a photomicrograph showing the crystal structure of a surfaceof an example 1b of a deposit layer after being polished;

FIG. 66A is a photomicrograph showing the crystal structure of a slidesurface in an example 1a of a slide surface construction;

FIG. 66B is a tracing of FIG. 66A;

FIG. 67 is a graph illustrating the relationship between the area rate Aof hexagonal pyramid-shaped Fe crystals and the seizure generating load;and

FIG. 68 is a graph illustrating the relationship between the area rate Aof hexagonal pyramid-shaped Fe crystals and the dynamic frictioncoefficient μ.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIRST EMBODIMENT

Referring to FIG. 1, a slide bearing 5 is disposed between a larger endhole 2 in a connecting rod 1 for an internal combustion engine and acrankpin 4 of a crankshaft 3. The slide surface bearing 5 is formed of apair of semi-annular halves 6 which have the same structure.

As shown in FIG. 2, in a backing plate 7 of each of the semi-annularhalves 6, a lamellar slide surface construction 9 is formed on an innerperipheral surface opposed to the crankpin 4 by plating.

FIG. 3 shows the developed semi-annular half 6 as flat. The slidesurface construction 9 includes a pair of narrow band-shaped firstregions R₁ extending over the entire length of opposite ends in an axialdirection "a" of the crankpin, and a wider band-shaped second region R₂located between the two first regions R₁. The first regions R₁ areplaced under a sliding condition more severe than that under which thesecond region R₂ is placed, due to the flexing of the crankpin 4. Asshown in FIGS. 2 and 3, an oil hole 10 is defined in a central portionof the semi-annular half 6. A chamfer 11 is provided in a portion of theoil hole 10 adjacent the slide surface construction 9.

As best shown in FIGS. 3 and 4, the slide surface construction 9 isformed of an aggregate of metal crystals. Preferably (2hhh) orientedmetal crystals 13 having a body-centered cubic (bcc) structure as shownin FIG. 5 with their (2hhh) planes (by Miller indices) oriented toward aslide surface 12 exist in the first region R₁. The content (whichindicates a presence or existing amount) S2_(hhh) of the (2hhh) orientedmetal crystals is set in a range of 20%≦S2_(hhh) ≦100% in the firstregion R₁. The lower limit value of the content S2_(hhh) is preferablyequal to 25%.

Preferably (hhh) oriented metal crystals 14 having a body-centered cubicstructure as shown in FIG. 5 with their (hhh) planes (by Miller indices)oriented toward a slide surface 12 exist in the second region R₂. Thecontent (which indicates a presence or existing amount) S_(hhh) of the(hhh) oriented metal crystals is set in a range of 40%≦S_(hhh) ≦100% inthe second region R₂.

In the first region R₁, the (2hhh) oriented metal crystals 13 are growninto a columnar shape from the inner peripheral surface 8 of the backingplate 7, with tip ends of the (2hhh) oriented metal crystals 13 beingformed of fish-shaped metal crystals 15 such as sardine-shaped metalcrystals in the slide surface 12. If the content S2_(hhh) of the (2hhh)oriented metal crystals 13 is set in the above-described range, theslide surface 12 takes on a very intricate aspect due to the largenumber of fish-shaped metal crystals existing in the slide surface 12,and hence, has a good oil retention. Moreover, the (2hhh) planes of the(2hhh) oriented metal crystals 13 are secondary slide faces and for thisreason, the crystals 13 have a high hardness and a high strength.

Such first region R₁ has excellent seizure and wear resistances andtherefore, even if the sliding condition is severe, the first region R₁can withstand such severe sliding condition.

In the second region R₂, the (hhh) oriented metal crystals 14 are growninto a columnar shape from the inner peripheral surface of the backingplate 7, with tip ends of the (hhh) oriented metal crystals 14 beingformed of hexagonal pyramid-shaped metal crystals 16 as clearly shown inFIG. 3, or trigonal pyramid-shaped metal crystals 17 as clearly shown inFIG. 6, in the slide surface 12. If the content S_(hhh) of the (hhh)oriented metal crystals 14 is set in the above-described range, theslide surface 12 takes on a very intricate aspect due to the largenumber of hexagonal pyramid-shaped metal crystals 16 and/or the largenumber of trigonal pyramid-shaped metal crystals 17 existing in theslide surface 12, and hence, has a good oil retention. However, the(hhh) oriented metal crystals 14 have a lower hardness, as compared withthe (2hhh) oriented metal crystals 13.

Such second region R₂ has an excellent seizure resistance and hence, ismost suitable for use in a site where the seizure resistance ispreferentially required.

As clearly shown in FIG. 7, the inclination of the (2hhh) plane withrespect to a phantom plane 18 along the slide surface 12 appears as theinclination of the fish-shaped metal crystal 15 and hence, an influenceis imparted to the oil retention and wear resistance of the first regionR₁. The inclination angle θ formed by the (2hhh) plane with respect tothe phantom plane 18 preferably is set in a range of 0°≦θ≦15°. In thiscase, the direction of inclination of the (2hhh) plane is not limited.If the inclination angle θ is larger than 15°, the oil retention and thewear resistance of the first region R₁ are reduced. The preferredinclination angle also applies to the (hhh) plane, as shown in FIG. 8.

Examples of the metal crystals having the bcc structure are those ofsimple metals such as Fe, Cr, Mo, W, Ta, Zr, Nb, V and the like, orthose of alloys thereof.

In the plating treatment for forming the first and second regions R₁ andR₂ of the slide surface construction, the range of conditions for aplating bath in carrying out an electrolytic Fe plating are as shown inTable 1. In this case, when one of the regions is formed, a portioncorresponding to the other region, or the other region is masked.

                  TABLE 1    ______________________________________                Plating bath                Ferrous    Slide surface                sulfate            Temperature    construction                (g/liter)   pH     (°C.)    ______________________________________    First and second                100-400     5-7    40-60    regions    ______________________________________

The adjustment of pH is carried out using ammonia water.

A pulse current process is mainly utilized as an energizing method. Inthe pulse current process, the electric current I from a plating powersource is controlled to describe a pulse waveform with the passage oftime T, so that the current I is increased from a minimum current valueImin and reaches a maximum current value Imax, and is then dropped tothe minimum current value Imin, as shown in FIG. 9. In FIG. 9, T_(ON) isan energization time from the start of the increase of the electric andcurrent and T_(C) is a cycle time, wherein one cycle is defined as beingfrom the start of an earlier increase to the start of a subsequentincrease.

                  TABLE 2    ______________________________________               Pulse current process    Slide surface                 CDmax   CDm             T.sub.ON    construction (A/dm.sup.2)                         (A/dm.sup.2)                                   T.sub.ON /T.sub.C                                         (msec)    ______________________________________    First and second                 ≧2.2                         ≧1.0                                   ≦0.45                                         ≦100    regions    ______________________________________

Table 2 shows the minimum or maximum conditions for carrying out thepulse current process. In Table 2, CDmax represents a maximum cathodecurrent density; CDm represents an average cathode current density; andT_(ON) /T_(C) represents a ratio of the energization time T_(ON) to thecycle time T_(C), i.e., a time ratio.

If the pulse current process is utilized, the ion concentration in thevicinity of a cathode is uniformized due to the fact that the maximumelectric current alternately flows and does not flow in the platingbath. Thus, the composition of the first and second regions R₁ and R₂can be stabilized.

In the above-described electrolytic Fe plating process, theprecipitation and content of the (2hhh) oriented Fe crystals or the(hhh) oriented Fe crystals are controlled by changing the plating bathconditions and the energizing conditions, as described below. Thiscontrol is easy under the utilization of the pulse current process andhence, the slide surface 12 is easily formed into an intended form.

In addition to the electrolytic Fe plating, other examples of a platingprocess are a PVD process, a CVD process, a sputtering process, an ionplating and the like, which are gas-phase plating processes.

Example-1

(a) Sliding Characteristic of First Region R₁

For each test example, a backing plate 7 made of a rolled sheet steel(JIS SPCC) and having an outside diameter of 51 mm (52.3 mm in a freestate), a width of 19.5 mm, a thickness of 1.485 mm and an oil hole 10diameter of 3 mm was prepared. Those portions of the inner peripheralsurface 8 of the backing plate 7 which correspond to the two firstregions R₁ were subjected to an electrolytic Fe plating to form firstregions R₁ formed of an aggregate of Fe crystals and having a width of 2mm and a thickness of 15 μm. During this time, that portion of thebacking plate 7 which corresponds to the second region R₂ was maskedusing a steel sheet as a conductive jig.

Then, the two first regions R₁ were masked in the same manner as thatdescribed above, and that portion of the backing plate 7 whichcorresponds to the second region R₂ was subjected to the electrolytic Feplating to form a second region R₂ having a thickness of 15 μm.

Table 3 shows the electrolytic Fe plating conditions for examples 1a to5a of the first regions, and Table 4 shows electrolytic Fe platingconditions for examples 6a to 9a of the first regions and an example 1bof the second region. The plating time was varied within a range of 5 to60 minutes in order to set the thickness for the examples 1a to 9a and1b at 15 μm, as described above.

                                      TABLE 3    __________________________________________________________________________    Plating bath    Ferrous             Pulse current process    First sulfate                 Temperature                        CDmax                            CDm    region          (g/liter)               pH                 (° C.)                        (A/dm.sup.2)                            (A/dm.sup.2)                                 T.sub.ON /T.sub.C                                     T.sub.ON (msec)    __________________________________________________________________________    Example 1a          400  6.5                 41.5   40  8    0.2 2    Example 2a          400  6.5                 41.5   30  6    0.2 2    Example 3a          400  6.3                 41.5   25  5    0.2 2    Example 4a          400  6.5                 43     30  6    0.2 2    Example 5a          400  6.3                 43     25  5    0.2 2    __________________________________________________________________________

                                      TABLE 4    __________________________________________________________________________           Plating bath           Ferrous       Pulse current process           sulfate                  Temperature                         CDmax                             CDm      T.sub.ON           (g/liter)               pH (° C.)                         (A/dm.sup.2)                             (A/dm.sup.2)                                  T.sub.ON /T.sub.C                                      (msec)    __________________________________________________________________________    First region    Example 6a           400 6.3                  45     25  5    0.2 2    Example 7a           400 6.2                  48     25  5    0.2 2    Example 8a           400 6.1                  48     25  5    0.2 2    Example 9a           400 6  48     25  5    0.2 2    Second region    Example 1b           400 6  48     25  5    0.2 2    __________________________________________________________________________

Tables 5 and 6 show the crystal form of the slide surface, the contentof the oriented Fe crystals and the hardness of a section of the slidesurface construction for the examples, with Table 5 corresponding to theexamples 1a to 5a, and Table 6 corresponding to the examples 6a to 9aand 1b.

                                      TABLE 5    __________________________________________________________________________    First Crystal form of slide                      Content S (%) of oriented Fe crystals                                      Hardness    region          surface     S.sub.110                         S.sub.200                            S.sub.211                                S.sub.310                                   S.sub.222                                      HmV    __________________________________________________________________________    Example 1a          Fish-shaped 5.4                         0.9                            91.3                                0  2.4                                      675    Example 2a          Fish-shaped 15.2                         7.9                            52.7                                8.6                                   15.6                                      634    Example 3a          Fish-shaped and granular                      20.8                         15 25.7                                16.4                                   22.1                                      584    Example 4a          Fish-shaped and hexagonal                      1  0  47.9                                0  51.1                                      581          pyramid-shaped    Example 5a          Fish-shaped and hexagonal                      14.8                         3.3                            25.9                                3.6                                   52.4                                      579          pyramid-shaped    __________________________________________________________________________

                                      TABLE 6    __________________________________________________________________________           Crystal form of slide                        Content S (%) of oriented Fe crystals                                        Hardness           surface      S.sub.110                           S.sub.200                              S.sub.211                                  S.sub.310                                     S.sub.222                                        HmV    __________________________________________________________________________    First region    Example 6a           Fish-shaped and                        0  0  25.2                                  0  74.8                                        523           hexagonal pyramid-shaped    Example 7a           Fish-shaped and                        0.1                           0  20.6                                  0  79.3                                        491           hexagonal pyramid-shaped    Example 8a           Hexagonal pyramid-shaped                        0  0  19.5                                  0  80.5                                        475           and granular    Example 9a           Hexagonal pyramid-shaped                        0.5                           0  1.4 0  98.1                                        420    Second region    Example 1b           Hexagonal pyramid-shaped                        0.5                           0  1.4 0  98.1                                        420    __________________________________________________________________________

The content of the oriented Fe crystals was determined using equationswhich will be described below, based on the X-ray diffraction patternsfor the examples 1a to 9a and 1b. As shown in FIG. 10, the X-raydiffraction was carried out at a 0° position where X-ray was applied atright angles to the slide surface 12, and a position where the slidesurface 12 was inclined at an inclination angle α, taking theinclination of the fish-shaped metal crystals and the like intoconsideration. In this case, α was set at 5°, 10° and 15°. The result ofmeasurement at the 0° position and the result of measurement at the 5°,10° and 15° position are substantially identical to each other andhence, the X-ray diffraction pattern at the 0° position was used for thecalculation of the content. FIGS. 11 and 12 show the X-ray diffractionpatterns for the examples 1a and 4a at the 0° position. In the followingequations, for example, the {110} oriented Fe crystal means an orientedFe crystal with its {110} plane oriented toward the slide surface.

{110} oriented Fe crystals: S₁₁₀ ={(I₁₁₀ /IA₁₁₀)/T}×100

{200} oriented Fe crystals: S₂₀₀ ={(I₂₀₀ /IA₂₀₀)/T}×100

{211} oriented Fe crystals: S₂₁₁ ={(I₂₁₁ /IA₂₁₁)/T}×100

{310} oriented Fe crystals: S₃₁₀ ={(I₃₁₀ /IA₃₁₀)/T}×100

{222} oriented Fe crystals: S₂₂₂ ={(I₂₂₂ /IA₂₂₂)/T}×100

wherein each of I₁₁₀, I₂₀₀, I₂₁₁, I₃₁₀ and I₂₂₂ is a measurement (cps)of an intensity of X-ray reflected from each crystal plane; each ofIA₁₁₀, IA₂₀₀, IA₂₁₁, IA₃₁₀ and IA₂₂₂ is an intensity ratio of X-raysreflected from crystal planes in an ASTM card, IA₁₁₀ =100; IA₂₀₀ =20,IA₂₁₁ =30; IA₃₁₀ =12; and IA₂₂₂ =6. Further, T=(I₁₁₀ /IA₁₁₀)+(I₂₀₀/IA₂₀₀)+(I₂₁₁ /IA₂₁₁)+(I₃₁₀ /IA₃₁₀)+(I₂₂₂ /IA₂₂₂).

FIG. 13 is a photomicrograph showing the crystal structure of the slidesurface in the example 1a. In FIG. 13, a large number of fish-shaped Fecrystals are observed. The fish-shaped Fe crystal is a {211} oriented Fecrystal with its {211} plane oriented toward the slide surface. Thecontent S₂₁₁ (S2_(hhh)) of the {211} oriented Fe crystals is equal to91.3%, as shown in Table 5 and FIG. 11.

FIG. 14 is a photomicrograph showing the crystal structure of the slidesurface in the example 4a. In FIG. 14, a large number of fish-shaped Fecrystals and a large number of hexagonal pyramid-shaped Fe crystals areobserved. The fish-shaped Fe crystal is a {211} oriented Fe crystal withits {211} plane oriented toward the slide surface. The content S₂₁₁ ofthe {211} oriented Fe crystals is equal to 47.9%, as shown in Table 5and FIG. 12. The hexagonal pyramid-shaped Fe crystal is a {222} orientedFe crystal with its (hhh) plane, i.e., {222} plane oriented toward theslide surface. The content S₂₂₂ (S_(hhh)) of the {222} oriented Fecrystals is equal to 51.1%, as shown in Table 5 and FIG. 12.

FIG. 15 is a photomicrograph showing the crystal structure of the slidesurface in the example 8a. In FIG. 15, a large number of hexagonalpyramid-shaped Fe crystals and a large number of granular Fe crystalsare observed. The hexagonal pyramid-shaped Fe crystal is likewise a{222} oriented Fe crystal with its {222} plane oriented toward the slidesurface. The content S₂₂₂ of the {222} oriented Fe crystals is equal to80.5%, as shown in Table 6.

In Tables 5 and 6, the examples 1a to 7a are high in hardness, ascompared with the examples 8a, 9a and 1b. This is attributable to thecontent S₂₁₁ of the {211} oriented Fe crystals being equal to or higherthan 20%. In this case, if S₂₁₁ ≧25%, the degree of increase in hardnessis remarkable.

In order to carry out a seizure test, a rotary shaft made of a carbonsteel (JIS S48C, a soft nitrided material) and having a diameter of47.94 mm and a length of 140 mm was placed in a housing (with aclearance of 30 μm) of a metal tester in such a manner that it wasclamped by a pair of slide bearings of semi-annular halves having theconstruction of example 1a for the first region and 1b for the secondregion. Then, the seizure test was carried out under conditions of thenumber of rotations of the rotary shaft being equal to 6000 rpm and theamount of oil supplied being equal to 600 ml/min, and by a method forapplying load to the slide bearings in such a manner that a load of2,000 N was first applied to the slide bearings and maintained for 2minutes, and after that, the load was increased in sequence by 2,000 Nwhile maintaining it for 2 minutes each time the load was increased.During this time, the temperature of those portions of the backing plateof the slide bearing corresponding to the two first regions wasmeasured, and the load at the time when the temperature exceeded 180° C.was defined as a seizure generating load. A similar seizure test wascarried out for the slide bearings each comprised of a pair ofsemi-annular halves having the construction of examples 2a to 9a in thefirst regions R₁ and the example 1b in the second region R₂.

Then, chips having the examples 1a to 9a were fabricated and subjectedto a wear test in a chip-on-disk manner under lubrication to measure awear amount. Conditions for the wear test are as follows: the materialfor the disk was a carbon steel (JIS S48C, a soft nitrided material);the peripheral speed of the disk was 12.5 m/sec; the amount of oilsupplied was 5 ml/min; the area of the slide surface of the chip was 1cm² ; the urging load on the chip was 300 N; the sliding time was 30minutes; and the wear amount was the difference between the thickness ofthe chip before the test and the thickness of the chip after the test.

Table 7 shows results of the seizure test and the wear test for theexamples 1a to 9a along with the ratio S₂₁₁ /S₂₂₂ of the content S₂₁₁ ofthe {211} oriented Fe crystals to the content S₂₂₂ of the {222} orientedFe crystals.

                  TABLE 7    ______________________________________                           Seizure                           generating                                    Wear amount    First region              Ratio S.sub.211 /S.sub.222                           load (N) (μm)    ______________________________________    Example 1a              38.0         54000    1.0    Example 2a              3.4          52000    1.2    Example 3a              1.2          48000    1.5    Example 4a              0.9          48000    1.9    Example 5a              0.5          46500    2.0    Example 6a              0.3          46000    2.2    Example 7a              0.3          37500    3.5    Example 8a              0.2          37000    3.7    Example 9a              0.01         36000    3.7    ______________________________________

FIG. 16 shows the relationship between the content S₂₁₁ of the {211}oriented Fe crystals and the seizure generating load for the examples 1ato 9a. In FIG. 16, points (1a) to (9a) correspond to the examples 1a to9a, respectively. The relationship between the points and the examplesapplies to Figures which will be described hereinafter.

FIG. 17 shows the relationship between the content S₂₁₁ of the {211}oriented Fe crystals and the wear amount for the examples 1a to 9a.

In FIGS. 16 and 17, the enhancement in seizure resistance and in wearresistance in examples 1a to 6a is distinct from the examples 7a, 8a and9a. From this, it can be seen that the content S₂₁₁ in the f irst regionR₁ may be set in a range of S₂₁₁ ≧20%. Preferably, the content S₂₁₁ isin a range of S₂₁₁ ≧25%.

If the ratio S₂₁₁ /S₂₂₂ is set in a range of S₂₁₁ /S₂₂₂ ≧1 when thecontent S₂₁₁ is equal to or higher than 25%, the seizure and wearresistances are enhanced remarkably, as in the examples 1a to 3a. In thecase of the example 4a, the content S₂₁₁ is relatively high, but theseizure resistance is equivalent to that of the example 3a having therelatively low content S₂₁₁, and the wear resistance is equivalent tothat of the example 5a having the relatively low content S₂₁₁, becausethe ratio S₂₁₁ /S₂₂₂ is lower than 1.

(b) Sliding Characteristic of Second Region R₂

For each test example, a backing plate 7 made of a rolled sheet steel(JIS SPCC) and having an outside diameter of 51 mm (52.3 mm in a freestate), a width of 19.5 mm, a thickness of 1.485 mm and an oil holediameter of 3 mm was prepared. That portion of the inner peripheralsurface 8 of the backing plate 7 which corresponds to the second regionsR₂ was subjected to an electrolytic Fe plating to form a second regionR₂ formed of an aggregate of Fe crystals and having a width of 15.5 mmand a thickness of 15 μm. During this time, those portions of thebacking plate 7 which corresponds to the two first regions R₁ weremasked using a steel sheet as a conductive jig.

Then, the second region R₂ was masked in the same manner as thatdescribed above, and those portions of the backing plate 7 whichcorrespond to the two first regions R₁ were subjected to theelectrolytic Fe plating to form two first regions R₁ having a thicknessof 15 μm.

Table 8 shows the electrolytic Fe plating conditions for examples 1b to5b of the second region and an example 1a of the first regions R₁. Theplating time was varied within a range of 5 to 60 minutes in order toset the thickness for the examples 1b to 5b and 1a at 15 μm, asdescribed above.

                                      TABLE 8    __________________________________________________________________________           Plating bath           Ferrous       Pulse current process           sulfate                  Temperature                         CDmax                             CDm      T.sub.ON           (g/liter)                pH                  (° C.)                         (A/dm.sup.2)                             (A/dm.sup.2)                                  T.sub.ON /T.sub.C                                      (msec)    __________________________________________________________________________    Second region    Example 1b           400  6 48     25  5    0.2 2    Example 2b           300  6 48     17.5                             3.5  0.2 2    Example 3b           300  6 48     15  3    0.2 2    Example 4b           400  4 50     20  4    0.2 2    Example 5b           400  3 50     20  4    0.2 2    First regions           400  6.5                  41.5   40  8    0.2 2    Example 1a    __________________________________________________________________________

Table 9 shows the crystal form of the slide surface, the content of theoriented Fe crystals, and the hardness of a section of the slide surfaceconstruction for the examples 1b to 5b and 1a.

                                      TABLE 9    __________________________________________________________________________    Crystal form of slide                      Content S (%) of oriented Fe crystals                                      Hardness    surface           S.sub.110                         S.sub.200                            S.sub.211                                S.sub.310                                   S.sub.222                                      HmV    __________________________________________________________________________    Second    region    Example 1b          Hexagonal pyramid-shaped                      0.5                         0  1.4 0  98.1                                      420    Example 2b          Hexagonal pyramid-                      11.3                         3.8                            22.2                                2  60.7                                      384          shaped, Fish-shaped and          granular    Example 3b          Hexagonal pyramid-                      17.5                         9.7                            20.3                                11.8                                   40.7                                      333          shaped, Fish-shaped and          granular    Example 4b          Hexagonal pyramid-shaped                      8.5                         15 18.9                                20.5                                   37.1                                      318          and granular    Example 5b          Granular    14.4                         19.7                            18.9                                24.5                                   22.5                                      285    First regions          Fish-shaped 5.4                         0.9                            91.3                                0  2.4                                      675    Example 1a    __________________________________________________________________________

The content of the oriented Fe crystals was determined in the samemanner as that described above, based on the X-ray diffraction patternsfor the examples 1b to 5b and 1a. FIG. 19 is an X-ray diffractionpattern at the 0° position for the example 5b.

FIG. 20 is a photomicrograph showing the crystal structure of the slidesurface in the example 1b. In FIG. 20, a large number of hexagonalpyramid-shaped Fe crystals are observed. The hexagonal pyramid-shaped Fecrystal is a {222} oriented Fe crystal with its (hhh) plane, i.e., {222}plane oriented toward the slide surface. The content S₂₂₂ (S_(hhh)) ofthe {222} oriented Fe crystals is equal to 98.1%, as shown in Table 9and FIG. 18.

FIG. 21 is a photomicrograph showing the crystal structure of the slidesurface in the example 5b. In FIG. 21, a large number of granular Fecrystals are observed. In this case, the content of the differentlyoriented Fe crystals is substantially averaged or equal, as shown Table9 and FIG. 19.

Then, a seizure test was carried out under the same conditions as thosedescribed above, using a slide bearing comprised of a pair ofsemi-annular halves having the construction of the examples 1b and 1afor the second and first regions, respectively, and using theabove-described metal tester. The measurement of the temperaturecorresponding to the seizure generating load was carried out for thatportion of the outer peripheral surface of the backing plate of theslide bearing which corresponds to the second region. A similar seizuretest was carried out using a slide bearing comprised of a pair ofsemi-annular halves having the construction of each of the examples 2bto 5b for the second region and 1a for the first region. Table 10 showsresults of the seizure test.

                  TABLE 10    ______________________________________    Second region                 Seizure generating load (N)    ______________________________________    Example 1b   36000    Example 2b   35000    Example 3b   32000    Example 4b   22000    Example 5b   21000    ______________________________________

FIG. 22 shows the relationship between the content S₂₂₂ of the {222}oriented Fe crystals and the seizure generating load for the examples 1bto 5b.

In FIG. 22, the enhancement in seizure resistance in examples 1b, 2b and3b is distinct from the examples 4b and 5b. From this, it can be seenthat the content S₂₂₂ in the second region R₂ may be set in a range ofS₂₂₂ ≧40%.

Example-2

A piston 19 for an internal combustion engine is shown in FIGS. 23A and23B and is formed of an aluminum alloy (JIS AC8A, a T7-treatedmaterial). A lamellar slide surface construction 9 is formed on theentire outer peripheral surface of a land portion 20 of the piston 19and on a portion of an outer peripheral surface of a skirt portion 21 ofthe piston 19.

In this case, the section located on the entire outer peripheral surfaceof the land portion 20 and the section located on a portion of the skirtportion 21 correspond to first regions R₁ of the slide surfaceconstruction 9. The term "a portion" of the skirt portion 21 correspondsto the portion obtained by excluding the two recesses 23 around twopiston pin holes 22 from the skirt portion 21, and two central portions24 surrounded by a one-dot and dashed line between both the recesses 23.Sections located at the two central portions surrounded by the one-dotand dashed line correspond to second regions R₂ of the slide surfaceconstruction 9.

Specifically, the sections of the piston 19 corresponding to the secondregions R₂ (namely, the two central portions) and the two recesses 23were masked by the same means as that described above, and slide surfaceconstructions of examples 1a to 9a of the first region R₁ described insection (a) above were formed on the sections corresponding to the firstregions R₁ by an electrolytic Fe plating process under the sameconditions as those described above. Then, the first regions R₁ weremasked by the same means as that described above, and a construction ofabove example 1b of the second region R₂ described in section (a) abovewas formed at each of the two central portion 24 and the two recesses 23by an electrolytic Fe plating process under the same conditions. In thiscase, the surface skins formed at the two recesses 23 and havinghexagonal pyramid-shaped Fe crystals in a surface thereof have an oilaccumulating function.

Then, chips having the examples 1a to 9a were fabricated and subjectedto a seizure test in a chip-on-disk manner under lubrication to measurethe seizure generating load, thereby providing results given in Table11. Conditions for the seizure test were as follows: the material forthe disk was a cast iron (JIS FC250); the peripheral speed of the diskwas 12.5 m/sec; the amount oil supplied was 40 ml/min; the area of theslide surface of the chip was 1 cm² ; the method for applying load tothe chip was to apply a load of 20 N to the chip and maintain it for 2minutes, and after that, the load was increased in sequence by 20 Nwhile maintaining it for 2 minutes each time whenever the load wasincreased.

                  TABLE 11    ______________________________________    First region Seizure generating load (N)    ______________________________________    Example 1a   2750    Example 2a   2680    Example 3a   2450    Example 4a   2420    Example 5a   2380    Example 6a   2350    Example 7a   1500    Example 8a   1480    Example 9a   1450    ______________________________________

FIG. 24 shows the relationship between the content S₂₁₁ of the {211}oriented Fe crystals and the seizure generating load for the examples 1ato 9a.

In FIG. 24, the enhancement in seizure resistance for examples 1a to 6ais distinct from the examples 7a to 9a. From this, it can be seen thatthe content S₂₁₁ in the first region R₁ may be set in a range of S₂₁₁≧20%. Preferably, the content S₂₁₁ is in a range of S₂₁₁ ≧25%.

If the ratio S₂₁₁ /S₂₂₂ is set in a range of S₂₁₁ /S₂₂₂ ≧1 when thecontent S₂₁₁ is equal to or higher than 25%, the seizure resistance isenhanced remarkably as in the examples 1a to 3a. In the case of theexample 4a, the content S₂₁₁ is relatively high, but the seizureresistance is equivalent to those of the examples 3a and 5a having therelatively low content S₂₁₁, because the ratio S₂₁₁ /S₂₂₂ is lower than1.

The first embodiment is not limited to the slide bearing and piston butis applicable to various slide members such as a balancer shaft, a camshaft, a piston pin and the like, which have two regions of differentsliding conditions.

SECOND EMBODIMENT

In a gearing device 25 shown in FIG. 25, two gears 26₁ and 26₂ meshedwith each other are formed of a steel. A lamellar slide surfaceconstruction 9 is formed on a meshed face of at least one of the gears26₁ by an electrolytic plating treatment.

The slide surface construction 9 is formed of an aggregate of metalcrystals having a body-centered cubic structure (which will be alsoreferred to as a bcc structure hereinafter), as in the first embodiment,as shown in FIG. 5. The aggregate includes a large number of columnarcrystals 28 grown from the meshed face 27, as shown in FIG. 26. Each ofthe columnar crystals 28 is at least one of a (hhh) oriented metalcrystal with its (hhh) plane (by Miller indices) oriented toward a slidesurface 12, and a (2hhh) oriented metal crystal with its (2hhh) plane(by Miller indices) oriented toward the slide surface 12.

When the columnar crystal 28 having the bcc structure as described aboveis the (hhh) oriented metal crystal with its (hhh) plane (by Millerindices) oriented toward the slide surface 12, the tip end of thecolumnar metal crystals can be formed into hexagonal pyramid-shapedmetal crystals (pyramid-shaped metal crystals) 16 in the slide surface12, as shown in FIG. 27. The hexagonal pyramid-shaped metal crystals 16are small in average grain size and substantially uniform in grain size,as compared with trigonal pyramid-shaped metal crystals (pyramid-shapedmetal crystals) which are likewise (hhh) oriented metal crystals. In thehexagonal pyramid-shaped metal crystals 16 and the like, the grain sizeand the height are in an interrelation to each other. Therefore, thegrain sizes being substantially uniform, indicates that the heights arealso substantially equal to one another.

As shown in FIGS. 26 and 28A, at least some of the hexagonalpyramid-shaped metal crystals 16 are heteromorphic hexagonalpyramid-shaped metal crystals (heteromorphic pyramid-shaped metalcrystals) 16₁. The heteromorphic hexagonal pyramid-shaped metal crystal16₁ has at least one notched recess 30 (one notched recess in theillustrated embodiment) in at least one ridgeline 29 (six ridgelines inthe illustrated embodiment).

Normal hexagonal pyramid-shaped metal crystals 16₂ having no notchedrecess 30 in the ridgeline 29 as clearly shown in FIGS. 26 and 28B areincluded in the hexagonal pyramid-shaped metal crystals 16.

The area rate A of the hexagonal pyramid-shaped metal crystals 16 suchas the normal hexagonal and heteromorphic hexagonal pyramid-shaped metalcrystals 16₂ and 16₁ in the slide surface 12 is set in a range of40%≦A≦100%. The area rate A was determined according to an equation,A=(c/b)×100(%), wherein b represents an area of the slide surface 12,and c represents an area occupied in the slide surface 12 by all thehexagonal pyramid-shaped metal crystals 16.

The pseudo-area rate B of the heteromorphic hexagonal pyramid-shapedmetal crystals 16₁ in the slide surface 12 is set in a range of20%≦B≦100%. The pseudo-area rate B was determined in the followingmanner: as shown in FIG. 26, a reference line segment d having apredetermined length L₁ in a direction perpendicular to the direction ofgrowth of the columnar crystals 28 is defined to pass through or in thevicinity of the bottoms of the normal hexagonal and heteromorphichexagonal pyramid-shaped metal crystals 16₂ and 16₁ in a verticalsection of the slide surface construction 9. The length of theheteromorphic hexagonal pyramid-shaped metal crystals 16₁ at or in thevicinity of their bottoms in the same direction as the lengthwisedirection of the reference line segment d is defined as L₂, and the sumof the lengths L₂ of all the heteromorphic hexagonal pyramid-shapedmetal crystals 16₁ included within the reference line segment d isdefined as nL₂ (wherein n is the number of heteromorphic hexagonalpyramid-shaped metal crystals 16₁, e.g., n=4 in the illustratedembodiment). Thus, the pseudo-area rate B was calculated according to anequation of B=nL₂ /L₁)×100(%). A photomicrograph is used for thiscalculation. The reason why such a method is employed is that even ifthe slide surface 12 is observed from above by a microscope, theheteromorphic hexagonal pyramid-shaped metal crystals 16₁ cannot bediscriminated.

If the area rate A of the hexagonal pyramid-shaped metal crystals 16 inthe slide surface 12 is set in the above-described range, adjacent onesof the hexagonal pyramid-shaped metal crystals 16 assume mutually bitingstates, as shown in FIG. 27. Thus, the slide surface 12 takes on a veryintricate aspect comprising a large number of extremely fine crests 31,a large number of extremely fine valleys 32 formed between the crests31, and a large number of extremely fine swamps 33 formed due to themutual biting of the crests 31. Therefore, the slide surface 12 exhibitsa good retention to solid and semi-solid lubricating agents. Moreover,because the pseudo-area rate B of the heteromorphic hexagonalpyramid-shaped metal crystals 16₁ is set in the above-described range,the notched recesses 30 in the heteromorphic hexagonal pyramid-shapedmetal crystals 16₁ exhibit an anchoring effect to the solid andsemi-solid lubricating agents, thereby doubling the retention.

In such slide surface construction 9, even if it is placed in a severesliding environment, the lubrication agent retention of the slidesurface construction 9 is maintained higher under lubrication, and thedispersion of a sliding load is provided under non-lubrication by thelarge number of fine hexagonal pyramid-shaped metal crystals 16. Thus,the slide surface construction 9 exhibits an excellent seizureresistance both under lubrication and under non-lubrication.

Further, as a result of uniform fine division of the hexagonalpyramid-shaped metal crystals 16, a local increase in surface pressurecan be avoided, and a fine division of the sliding load can be achieved.Thus, the slide surface construction 9 exhibits an excellent wearresistance not only under lubrication but also under non-lubrication.

When the columnar crystals having the bcc structure are (2hhh) orientedmetal crystals with their (2hhh) planes (by Miller indices) orientedtoward the slide surface 12, tip ends of the columnar crystals can beformed into small pyramid-shaped metal crystals (pyramid-shaped metalcrystals).

Even when the hexagonal and trigonal pyramid-shaped metal crystals andthe small pyramid-shaped metal crystals exist in the slide surface, thearea rate A of the pyramid-shaped metal crystals is likewise set in arange of 40%≦A≦100%. Again, when the hexagonal and trigonalpyramid-shaped metal crystals and the small pyramid-shaped metalcrystals exist in the slide surface, the pseudo-area rate B of theheteromorphic pyramid-shaped metal crystals is likewise set in a rangeof 20%≦B≦100%.

As shown in FIG. 8, the inclination of the (hhh) plane with respect tothe phantom plane 18 along the slide surface 18 appears as theinclination of the hexagonal pyramid-shaped metal crystals 16 and hence,an influence is imparted to the lubricant retention and the wearresistance of the slide surface construction 9. The inclination angle θformed by the (hhh) plane with respect to the phantom plane 18 is set ina range of 0°≦θ≦15°, as in the first embodiment. In this case, thedirection of inclination of the (hhh) plane is not limited. If theinclination angle θ is higher than 15°, the lubricant retention and thewear resistance of the slide surface construction 9 are reduced. Theinclination θ also applies to the (2hhh) plane.

Examples of the metal crystals having the bcc structure are those ofsimple metals such as Fe, Cr, Mo, W, Ta, Zr, Nb, V and the like, orthose of alloys thereof, as in the first embodiment.

In the electrolytic plating process for forming the slide surfaceconstruction 9, the conditions for a plating bath in carrying out anelectrolytic Fe plating are as shown in Table 12.

                  TABLE 12    ______________________________________    Plating bath    Ferrous sulfate    (g/liter)       pH     Temperature (°C.)    ______________________________________    100-400         3-7    40-60    ______________________________________

The adjustment of pH of the plating bath is carried out using ammoniawater.

The electrolytic Fe plating process is divided into a plurality of steps(two steps, in the embodiment). In the first and second steps, a pulsecurrent process is utilized as an energizing method. In the pulsecurrent process, electric current I from a plating power source iscontrolled to describe a pulse waveform with the passage of time T, sothat the current I is increased from a minimum current value Imin(including Imin=0) and reaches a maximum current value Imax, and is thendropped to the minimum current value Imin, as shown in FIG. 29.

An energization stopping step for bringing the energizing electriccurrent into zero is interposed between the first step (the proceedingstep) and the second step (the succeeding step). A relationship, T₂ ≧100T₁ is established between the time T₂ required for the energizationstopping step and the minimum electric current maintaining time T₁ inthe first step. In this case, the minimum electric current maintainingtime T₁ in the first step is set in a range of T₁ ≧2.2 msec.

A relationship, CD₂ ≧1.2 CD₁ is established between the average cathodecurrent density CD₂ in the second step and the average cathode currentdensity CD₁ in the first step. In this case, the average cathode currentdensity CD₁ in the first step is set in a range of CD₁ ≧2.2 A/dm², andthe maximum cathode current density CDmax in the first and second stepsis set in a range of CDmax≧2.6 A/dm².

Further, if the energization time period from the start of theincreasing of the electric current I to the start of the dropping isrepresented by T₃, and a cycle time period is represented by T₄ whereinone cycle is defined as being from the start of the proceedingincreasing to the start succeeding increasing of the electric current,the ratio of the energization time period T₃ to the cycle time periodT₄, i.e., the time ratio T₃ /T₄ is set in a range of T₃ /T₄ ≦0.45 in thefirst and second steps. If T₃ /T₄ >0.45, the area rate A of thepyramid-shaped Fe crystals in the slide surface may be lower than 40% insome cases, depending upon other conditions.

A slide surface construction having the above-described structure can beeasily mass-produced by utilizing such electrolytic Fe plating process.

Example-1

As a simulation of a gear 26₁, a slide surface construction 9 formed ofan aggregate of Fe crystals and having a thickness of 15 μm was formedby subjecting an outer periphery of one surface of a disk made of achromemolybdenum steel (JIS SCM420, a carburized material) to anelectrolytic Fe plating process comprising first and second steps oronly a first step.

Table 13 shows the conditions for the plating bath for examples 1 to 15of slide surface constructions, and Tables 14 and 15 show energizingconditions for the examples 1 to 15.

                  TABLE 13    ______________________________________               Plating bath               Ferrous    Slide surface               sulfate            Temperature    construction               (g/liter)    pH    (°C.)    ______________________________________    Example 1  400          6     55    Example 2  300          6     55    Example 3  250          5.5   55    Example 4  400          6     50    Example 5  400          6     50    Example 6  300          6     50    Example 7  250          5.5   50    Example 8  400          6     50    Example 9  300          6     50    Example 10 250          5.5   50    Example 11 400          6     50    Example 12 300          6     50    Example 13 250          5.5   50    Example 14 200          4.5   50    Example 15 200          3     50    ______________________________________

                                      TABLE 14    __________________________________________________________________________                                      Energization    Slide First step                  stopping    surface          T.sub.3              T.sub.1        CDmax                                 Plating                                      step T.sub.2    construction          (msec)              (msec)                   T.sub.3 /T.sub.4                      CD.sub.1 (A/dm.sup.2)                             (A/dm.sup.2)                                 time (min)                                      (sec)    __________________________________________________________________________    Example 1          2   8    0.2                      4      20  12   1 (125T.sub.1)    Example 2          2   8    0.2                      3.5    17.5                                 13.7    Example 3          2   8    0. 2                      3      15  16    Example 4          2   8    0.2                      4      20  12    Example 5          2   8    0.2                      4      20  12    Example 6          2   8    0.2                      3.5    17.5                                 13.7    Example 7          2   8    0.2                      3      15  16    __________________________________________________________________________    Slide Second step    surface          T.sub.3              T.sub.1        CDmax                                 Plating    construction          (msec)              (msec)                   T.sub.3 /T.sub.4                      CD.sub.2 (A/dm.sup.2)                             (A/dm.sup.2)                                 time (min)    __________________________________________________________________________    Example 1          1   19   0.05                      7.2 (1.8 CD.sub.1)                             144 1.7    Example 2          1   19   0.05                      6.3 (1.8 CD.sub.1)                             126 1.9    Example 3          1   9    0.1                      5.4 (1.8 CD.sub.1)                             54  2.2    Example 4          1   9    0.1                      5.2 (1.3 CD.sub.1)                             52  2.3    Example 5          2   8    0.2                      4.8 (1.2 CD.sub.1)                             24  2.5    Example 6          2   8    0.2                      4.2 (1.2 CD.sub.1)                             21  2.9    Example 7          2   8    0.2                      3.6 (1.2 CD.sub.1)                             18  3.3    __________________________________________________________________________

                                      TABLE 15    __________________________________________________________________________                                      Energization    Slide First step                  stopping    surface          T.sub.3              T.sub.1        CDmax                                 Plating                                      step T.sub.2    construction          (msec)              (msec)                   T.sub.3 /T.sub.4                      CD.sub.1 (A/dm.sup.2)                             (A/dm.sup.2)                                 time (min)                                      (sec)    __________________________________________________________________________    Example 8          2   8    0.2                      4      20  12   1 (125T.sub.1)    Example 9          2   8    0.2                      3.5    17.5                                 13.7    Example 10          2   8    0.2                      3      15  16    Example 11          2   8    0.2                      4      20  15    Example 12          2   8    0.2                      3.5    17.5                                 17.1    Example 13          2   8    0.2                      3      15  20    Example 14          2   8    0.2                      3.5    17.5                                 17.1    Example 15          2   8    0.2                      0.5    2.5 120    __________________________________________________________________________    Slide Second step    surface          T.sub.3              T.sub.1        CDmax                                 Plating    construction          (msec)              (msec)                   T.sub.3 /T.sub.4                      CD.sub.2 (A/dm.sup.2)                             (A/dm.sup.2)                                 time (min)    __________________________________________________________________________    Example 8          3   7    0.3                      4.4 (1.1 CD.sub.1)                             14.7                                 2.7    Example 9          3   7    0.3                      3.9 (1.1 CD.sub.1)                             13  3.1    Example 10          3   7    0.3                      3.3 (1.1 CD.sub.1)                             11  3.6    Example 11          --  --   -- --     --  --    Example 12          --  --   -- --     --  --    Example 13          --  --   -- --     --  --    Example 14          --  --   -- --     --  --    Example 15          --  --   -- --     --  --    __________________________________________________________________________

Table 16 shows the content S of the oriented Fe crystals for theexamples 1 to 15.

                  TABLE 16    ______________________________________    Slide    surface Content S (%) of oriented Fe crystals    construction            {110}    {200}    {211}  {310}  {222}    ______________________________________    Example 1            0        0        3.8    0      96.2    Example 2            7.1      2.8      20.1   1.1    68.9    Example 3            19.3     4.6      33.8   2      40.3    Example 4            0        0        3.2    0      96.8    Example 5            0        0        2.7    0      97.3    Example 6            6.6      2.5      18.3   0.5    72.1    Example 7            18.7     5        34.1   0.7    41.5    Example 8            0.3      0        4.5    0      95.2    Example 9            6.1      3.1      19.4   1.2    70.2    Example 10            19.5     4.9      33.1   1.7    40.8    Example 11            0        0        3.5    0      96.5    Example 12            6        3.9      17.6   2.6    69.9    Example 13            21.8     3.5      30.8   2.4    41.5    Example 14            19.4     12.4     19.7   13     35.5    Example 15            33.6     16.5     17.5   17.7   14.7    ______________________________________

The content S was determined in the same manner as in the firstembodiment, based on the X-ray diffraction patterns (X-ray was appliedin a direction perpendicular to the slide surface) for the examples 1 to15. FIG. 30 is the X-ray diffraction pattern for the example 1; FIG. 31is the X-ray diffraction pattern for the example 11, and FIG. 32 is theX-ray diffraction pattern for the example 15.

Table 17 shows the crystal form of the slide surface, the area rate Aand grain size of the hexagonal pyramid-shaped Fe crystals in the slidesurface, the pseudo-area rate B of heteromorphic hexagonalpyramid-shaped Fe crystals, and the hardness of a vertical section ofthe slide surface construction.

                                      TABLE 17    __________________________________________________________________________                                Pseudo-area                                rate B (%) of                      Hexagonal pyramid                                heteromorphic    Slide             shaped Fe crystals                                hexagonal    Surface          Crystal form of slide                      Area rate                           Grain size                                pyramid-shaped                                        Hardness    Construction          surface     A (%)                           (μm)                                Fe crystals                                        HmV    __________________________________________________________________________    Example 1          hexagonal pyramid-shaped                      100  2.5  100     405    Example 2          hexagonal pyramid-                      70   2.7  72.4    381          shaped, small pyramid-          shaped and granular    Example 3          hexagonal pyramid-shaped                      40   3.3  41.1    293          and granular    Example 4          hexagonal pyramid-shaped                      100  2.5  40.8    398    Example 5          hexagonal pyramid-shaped                      100  2.5  20.5    401    Example 6          hexagonal pyramid-                      70   2.8  20.1    390          shaped, small pyramid-          shaped and granular    Example 7          hexagonal pyramid-shaped                      40   3.3  20.8    305          and granular    Example 8          hexagonal pyramid-shaped                      100  2.5  19.1    399    Example 9          hexagonal pyramid-                      70   2.7  19.3    390          shaped, small pyramid-          shaped and granular    Example 10          hexagonal pyramid-shaped                      40   3.3  18.8    305          and granular    Example 11          hexagonal pyramid-shaped                      100  2.5  0       395    Example 12          hexagonal pyramid-                      70   2.7  0       379          shaped, small pyramid-          shaped and granular    Example 13          hexagonal pyramid-shaped                      40   3.3  0       288          and granular    Example 14          hexagonal pyramid-shaped                      35   1.8  0       216          and granular    Example 15          granular    0    ≦0.1                                0       175    __________________________________________________________________________

The grain size of the hexagonal pyramid-shaped Fe crystals is an averagevalue of distances between opposed corners on the opposite sides of anapex, i.e., of lengths of three diagonal lines. In calculating thepseudo-area rate B of the heteromorphic hexagonal pyramid-shaped Fecrystals, a notch was provided in a disk, and then, the disk was cooledfor 5 minutes or more in liquid nitrogen. Thereafter, the disk and theslide surface construction were broken at the notch, and aphotomicrograph of the vertical section of the slide surfaceconstruction was taken. In this way, the pseudo-area rate B of theheteromorphic hexagonal pyramid-shaped Fe crystals was determined basedon such photomicrograph in the above-described manner.

FIG. 33 A is a photomicrograph showing the crystal structure of theslide surface in the example 1, and FIG. 33B is a photomicrographshowing the crystal structure of a vertical section in the example 1.FIG. 33C is an enlarged photomicrograph showing an essential portionshown in FIG. 33B. In FIG. 33A, a large number of hexagonalpyramid-shaped Fe crystals are observed. In this case, the area rate Aof the hexagonal pyramid-shaped Fe crystals is equal to 100%, as shownin Table 17. Each of the hexagonal pyramid-shaped Fe crystal is a {222}oriented Fe crystal with its (hhh) plane, i.e., {222} plane orientedtoward the slide surface. The content S of the {222} oriented Fecrystals is equal to 96.2%, as shown in Table 16 and FIG. 30. Thehexagonal pyramid-shaped Fe crystal are heteromorphic hexagonalpyramid-shaped Fe crystals each having notched recess(es), as apparentfrom FIGS. 33B and 33C. The pseudo-area rate B of the heteromorphichexagonal pyramid-shaped Fe crystals is equal to 100%, as shown in Table17.

FIG. 34 is a photomicrograph showing the crystal structure of the slidesurface in the example 11, wherein a large number of hexagonalpyramid-shaped Fe crystals are observed. In this case, the area rate Aof the hexagonal pyramid-shaped Fe crystals is equal to 100%, as shownin Table 17. Each of the hexagonal pyramid-shaped Fe crystals islikewise a {222} oriented Fe crystal. The content S of the {222}oriented Fe crystals is equal to 96.5%, as shown in Table 16 and FIG.31. However, the hexagonal pyramid-shaped Fe crystal are normalhexagonal pyramid-shaped Fe crystals and hence, the pseudo-area rate Bof the heteromorphic hexagonal pyramid-shaped Fe crystals is equal to0%, as shown in Table 17.

FIG. 35 is a photomicrograph showing the crystal structure of the slidesurface in the example 15, wherein a large number of granular Fecrystals are observed. In this case, the area rate of the hexagonalpyramid-shaped Fe crystals is equal to 0%, as shown in Table 17.

Then, disks having the slide surface construction of the examples 1 to15 were subjected to a seizure test in a chip-on-disk manner underlubrication to measure the seizure generating load, thereby providingthe results given in Table 18. The conditions for the seizure test wereas follows: the material for the chip was chromemolybdenum steel (JISSCM429, a carburized material); the peripheral speed of the disk was 15m/sec; the lubricating method was to apply a molybdenum disulfide onto asurface of each example of the disk; the area of the slide surface ofthe chip was 1 cm² ; and the method for applying load to the chip was toapply first a load of 20 N and maintain it for 2 minutes and after that,the load was increased in sequence by 20 N while maintaining it for 2minutes each time the load was increased.

                  TABLE 18    ______________________________________    Slide surface construction                     Seizure generating load (N)    ______________________________________    Example 1        740    Example 2        710    Example 3        630    Example 4        650    Example 5        550    Example 6        540    Example 7        520    Example 8        410    Example 9        410    Example 10       380    Example 11       400    Example 12       400    Example 13       370    Example 14       230    Example 15       220    ______________________________________

FIG. 36 shows the relationship between the area rate A of the hexagonalpyramid-shaped Fe crystals and the seizure generating load.

If the examples 1 to 13 are compared with the examples 14 and 15 in FIG.36, the former examples are substantially higher in seizure generatingload, as compared with the latter examples. From this, it can be seenthat the area rate of the hexagonal pyramid-shaped Fe crystals in theslide surface advantageously may be set in a range of A≧40%.

If the examples 1 to 7 are compared with the examples 8 to 13 when thearea rate A is equal to or higher than 40%, the former examples have aseizure resistance superior to the latter examples. From this, it can beseen that the pseudo-area rate B of the heteromorphic hexagonalpyramid-shaped Fe crystals advantageously may be set in a range ofB≧20%.

Then, using disks having the construction of examples 1 to 3 and 11 to15, the dynamic friction coefficient μ was measured in a chip-on-diskmanner under lubrication, thereby providing the results given in Table19. The conditions for this test are were follows: the material for thechip was chromemolybdenum steel (JIS SCM420, a carburized material); theperipheral speed of the disk was 15 m/sec; a lubricating oilcorresponding to 10W-30 at room temperature (in SAE viscosityclassification) was used; the amount of oil supplied was 40 ml/min; thearea of the slide surface of the chip was 1 cm² ; the method forapplying load to the chip was to first apply a load of 50 N and maintainit for 2 minutes and after that, the load was increased in sequence by50 N while maintaining it each time the load was increased. When theload reached 250 N, the chip was maintained for 5 minutes and thedynamic friction coefficient μ was measured.

                  TABLE 19    ______________________________________    Slide surface construction                    Dynamic friction coefficient μ    ______________________________________    Example 1       0.014    Example 2       0.014    Example 3       0.016    Example 11      0.013    Example 12      0.014    Example 13      0.015    Example 14      0.04    Example 15      0.042    ______________________________________

FIG. 37 shows the relationship between the area rate A of the hexagonalpyramid-shaped Fe crystals and the dynamic friction coefficient μ.

As is apparent from FIG. 37, when the area rate A of the hexagonalpyramid-shaped Fe crystals in the slide surface is equal to or higherthan 40%, the dynamic friction coefficients μ of the examples 1 to 3including the heteromorphic hexagonal pyramid-shaped Fe crystalsexisting in the slide surface are substantially equal to those of theexamples 11 to 13 including no heteromorphic hexagonal pyramid-shaped Fecrystals existing in the slide surface. From this, it can be seen thatthe existence of the heteromorphic hexagonal pyramid-shaped Fe crystalsin the slide surface does not exert any influence on the wear resistanceof the slide surface construction.

Example-2

A slide surface construction 9 formed of an aggregate of Fe crystals andhaving a thickness of 15 μm was formed on a meshed face 27 of a gear 26made of a chromemolybdenum steel (JIS SCM420, a carburized material) byan electrolytic Fe plating process comprising first and second steps.

Table 20 shows the conditions for the plating bath for examples 1 to 12of the slide surface construction, and Tables 21 and 22 show energizingconditions for the examples 1 to 12.

                  TABLE 20    ______________________________________    Plating bath    Ferrous sulfate (g/liter)                      pH    Temperature (°C.)    ______________________________________    400               6     50    ______________________________________

                                      TABLE 21    __________________________________________________________________________    Slide First step                Energization    surface          T.sub.3              T.sub.1      CDmax                               Plating                                    stopping step    construction          (msec)              (msec)                  T.sub.3 /T.sub.4                     CD.sub.1 (A/dm.sup.2)                           (A/dm.sup.2)                               time (min)                                    T.sub.2 (msec)    __________________________________________________________________________    Example 1          2   8   0.2                     4     20  12   800 (100T.sub.1)    Example 2    Example 3    Example 4    Example 5    Example 6                       8000 (1000T.sub.1)    __________________________________________________________________________    Second step    Slide                      Plating    surface          T.sub.3              T.sub.1      CDmax                               time    construction          (msec)              (msec)                  T.sub.3 /T.sub.4                     CD.sub.2 (A/dm.sup.2)                           (A/dm.sup.2)                               (min)    __________________________________________________________________________    Example 1          2   8   0.2                     6 (1.5 CD.sub.1)                           30  2    Example 2        5.6   28  2.1                     (1.4 CD.sub.1)    Example 3        4.8   24  2.5                     (1.2 CD.sub.1)    Example 4        4.4   22  2.7                     (1.1 CD.sub.1)    Example 5        4 (1.0 CD.sub.1)                           20  3    Example 6        5.2   26  2.3                     (1.3 CD.sub.1)    __________________________________________________________________________

                                      TABLE 22    __________________________________________________________________________    Slide First step                Energization    surface          T.sub.3              T.sub.1      CDmax                               Plating                                    stopping step    construction          (msec)              (msec)                  T.sub.3 /T.sub.4                     CD.sub.1 (A/dm.sup.2)                           (A/dm.sup.2)                               time (min)                                    T.sub.2 (msec)    __________________________________________________________________________    Example 7          2   8   0.2                     4     20  12   720 (90T.sub.1)    Example 8    Example 9    Example 10    Example 11    Example 12                      792 (99T.sub.1)    __________________________________________________________________________    Slide Second step    surface          T.sub.3              T.sub.1      CDmax                               Plating    construction          (msec)              (msec)                  T.sub.3 /T.sub.4                     CD.sub.1 (A/dm.sup.2)                           (A/dm.sup.2)                               time (min)    __________________________________________________________________________    Example 7          2   8   0.2                     6 (1.5 CD.sub.1)                           30  2    Example 8        5.6   28  2.1                     (1.4 CD.sub.1)    Example 9        4.8   24  2.5                     (1.2 CD.sub.1)    Example 10       4.4   22  2.7                     (1.1 CD.sub.1)    Example 11       4 (1.0 CD.sub.1)                           20  3    Example 12       5.2   26  2.3                     (1.3 CD.sub.1)    __________________________________________________________________________

Table 23 shows the content S of the oriented Fe crystals for theexamples 1 to 12. The content S was determined in the same manner as inthe first embodiment.

                  TABLE 23    ______________________________________    Slide surface            Content S (%) of oriented Fe crystals    construction            {110}    {200}    {211}  {310}  {222}    ______________________________________    Example 1            0        0        1.9    0      98.1    Example 2            0        0        3.1    0      96.9    Example 3            0        0        2.7    0      97.3    Example 4            0.3      0        4.5    0      95.2    Example 5            0.2      0        3.7    0      96.1    Example 6            0        0        3.2    0      96.8    Example 7            0        0        4.1    0      95.9    Example 8            0.4      0        3      0      96.6    Example 9            0        0        2.8    0      97.2    Example 10            0        0        4.2    0      95.8    Example 11            0.1      0        3.2    0      96.7    Example 12            0        0        3.9    0      96.1    ______________________________________

Table 24 shows the crystal form of the slide surface, the area rate Aand grain size of the hexagonal pyramid-shaped Fe crystals in the slidesurface, the pseudo-area rate B of the heteromorphic hexagonalpyramid-shaped Fe crystals, and the hardness of a vertical section ofthe slide surface construction for the examples 1 to 12. The area rateA, the grain size and the pseudo-area rate B were determined in the samemanner as that described above.

                                      TABLE 24    __________________________________________________________________________                  Hexagonal pyramid-                            Pseudo-area rate B (%) of    Slide Crystal form                  shaped Fe crystals                            heteromorphic hexagonal    surface          of slide                  Area rate                       Grain                            pyramid-shaped Fe                                        Hardness    construction          surface A (%)                       size (μm)                            crystals    HmV    __________________________________________________________________________    Example 1          Hexagonal                  100  2.5  100         408    Example 2          pyramid-shaped    89.4    Example 3               20.5    Example 4               19.1    Example 5               0    Example 6               40.8    Example 7               12.3    Example 8               12.4    Example 9               11.8    Example 10              12.1    Example 11              0    Example 12              16.1    __________________________________________________________________________

FIG. 38 shows the relationship between the average cathode currentdensity CD₂ in the second step and the pseudo-area rate B (%) of theheteromorphic hexagonal pyramid-shaped Fe crystals by the time T₂required for the energization stopping step.

As apparent from Table 24 and FIG. 38, the pseudo-area rate B of theheteromorphic hexagonal pyramid-shaped Fe crystals in the slide surfacefor the examples 1 to 3 and 6 is equal to or higher than 20%. From this,it may be safely mentioned that in order to set the pseudo-area rate Bin a range of B≧20%, it is necessary to establish a relation, T₂ ≧100 T₁between the time T₂ required for the energization stopping step and theminimum current maintaining time T₁, and to establish a relation, CD₂≧1.2 CD₁ between the average cathode current density CD₂ in the secondstep and the average cathode current density CD₂ in the first step.

The second embodiment is not limited to the gear, and is applicable to aquick joint, an upper arm, a lower arm and the like to which a solid orsemi-solid lubricating agent is applied. In this case, theresponsiveness is enhanced by a reduction in friction.

THIRD EMBODIMENT

Referring to FIG. 39, a cylinder block 34 for an internal combustionengine includes a cylinder block body 35 made of an aluminum alloy, anda cylinder sleeve 36 made of a cast iron. A lamellar slide surfaceconstruction 9 is formed on an inner peripheral surface 37 of thecylinder sleeve 36 by a plating treatment. A piston 19 made of analuminum alloy is slidably received in the cylinder sleeve 36.

The slide surface construction 9 is formed of an aggregate of metalcrystals having a body-centered cubic structure (which will be alsoreferred to as a bcc structure hereinafter), as shown in FIG. 5. Theaggregate includes a large number of (hhh) oriented metal crystals 14which are grown into a columnar shape from the inner peripheral surface37 of the cylinder sleeve 36 with their (hhh) planes (by Miller indices)oriented toward a slide surface 12, or a large number of (2hhh) orientedmetal crystals 14 which are grown into a columnar shape from the innerperipheral surface 37 of the cylinder sleeve 36 with their (2hhh) planes(by Miller indices) oriented toward the slide surface 12, as shown inFIG. 40.

When the aggregate of the metal crystals having the bcc structureincludes the large number of (hhh) oriented metal crystals 14 grown intoa columnar shape from the inner peripheral surface 37 of the cylindersleeve 36 with their (hhh) planes (by Miller indices) oriented towardthe slide surface 12, as described above, the tip ends of the (hhh)oriented metal crystals 14 can be formed into rounded hexagonalpyramid-shaped metal crystals (rounded pyramid-shaped metal crystals) 38in the slide surface, as shown in FIGS. 41, 42A and 42B. The roundedhexagonal pyramid-shaped metal crystals 38 are small in average grainsize and substantially uniform in grain size, as compared with roundedtrigonal pyramid-shaped metal crystals which are likewise (hhh) orientedmetal crystals. In the rounded hexagonal pyramid-shaped metal crystals38, there is an interrelation between the grain size and the height.Therefore, the grain size being substantially uniform, indicates thatthe heights are substantially equal to one another.

Each of ridgelines 39 in the rounded hexagonal pyramid-shaped metalcrystal 38 assumes a convex arcuate shape, and each slope-correspondencearea 40 between the adjacent ridgelines 39 comprises two band-likeregions each of which is one of two slopes forming each ridgeline 39,and a V groove-like region 44 which is connected to both the band-likeregion and whose opening width is gradually reduced from a skirt portion42 toward an apex 43.

The area rate A of the rounded hexagonal pyramid-shaped metal crystals38 in the slide surface 12 is set in a range of 40%≦A≦100%.

If the area rate A is set in such range, adjacent ones of the roundedhexagonal pyramid-shaped metal crystals 38 assume mutually bitingstates, as shown in FIG. 41. Thus, the slide surface takes on a veryintricate aspect comprising a large number of extremely fine crests 31,a large number of extremely fine valleys 32 formed between the crests31, and a large number of extremely fine swamps 33 formed due to themutual biting of the crests 31.

In this case, if each of the ridgelines 39 of the hexagonalpyramid-shaped metal crystal 16 is rectilinear and the apex 43 of thehexagonal pyramid-shaped metal crystal 16 is pointed, as shown in FIG.43, and if the slope-correspondence area 40 between the adjacentridgelines 39 is formed into a relatively deep V groove-like shape suchthat the opening width is gradually reduced from the skirt portion 42toward the apex 43, namely, if the hexagonal pyramid-shaped metalcrystals 16 are angular, the flow of oil lacks a smoothness, when theviscosity of the oil is high at a lower temperature or the like, becausethe angular pyramid-shaped metal crystals 16 performs an occludingeffect.

In contrast, if the rounded pyramid-shaped metal crystals 38 asdescribed above are formed to exist in the slide surface 12, the flowresistance of the oil with a high viscosity is reduced in the slidesurface 12 and therefore, the oil can be allowed to flow smoothly. Thus,the shear resistance of an oil film formed on the slide surface 12 canbe reduced to reduce the friction loss.

From the fact that the slide surface 12 takes on the very intricateaspect, as described above, the slide surface construction 9 has a goodoil retention, substantially irrespective of the viscosity of the oil.Thus, the slide surface construction 9 exhibits an excellent seizureresistance, even if it is placed in a severe sliding environment. On theother hand, even under non-lubrication, the dispersion of a sliding loadis provided by the large number of fine rounded hexagonal pyramid-shapedmetal crystals 38 and therefore, the seizure resistance of the slidesurface construction 9 is relatively good.

Further, as a result, uniform fine division of the rounded hexagonalpyramid-shaped metal crystals 38, a local increase in surface pressurecan be avoided and a fine division of the sliding load can be achieved.Thus, the slide surface construction 9 exhibits an excellent wearresistance not only under lubrication but also under non-lubrication.

In the rounded hexagonal pyramid-shaped metal crystals 38, it ispossible to form a valley portion 45 of the V groove-like region 44, sothat the valley portion 45 assumes a convex arcuate shape to follow theridgeline 39. If the valley portion 45 is formed in this manner, the Vgroove-like region 44 becomes narrow and hence, the flowability of ahigh-viscosity oil can be further enhanced.

When the aggregate of the metal crystals having the bcc structureincludes the large number of (2hhh) oriented metal crystals with their(2hhh) plane (by Miller indices) oriented toward the slide surface 12,the tip ends of the (2hhh) oriented metal crystals can be formed intorounded small pyramid-shaped metal crystals. Even when the roundedpyramid-shaped metal crystals such as the rounded hexagonal and trigonalpyramid-shaped and small pyramid-shaped metal crystals exists incombination in the slide surface 12, the area rate A of these roundedpyramid-shaped metal crystals in the slide surface 12 is set in a rangeof 40%≦A≦100%.

As shown in FIG. 8, the inclination of the (hhh) plane with respect tothe phantom plane 18 along the slide surface 12 appears as theinclination of the rounded hexagonal pyramid-shaped metal crystals 38and the like and hence, an influence is imparted to the oil retentionand the wear resistance of the slide surface construction. Theinclination angle θ formed by the (hhh) plane with respect to thephantom plane 18 is set in a range of 0°≦θ≦15° as in the firstembodiment. In this case, the direction of inclination of the (hhh)plane is not limited. If the inclination angle θ is larger than 15°, theoil retention and the wear resistance of the first region R₁ arereduced. The inclination angle θ also applies to the (2hhh) plane.

Examples of the metal crystals having the bcc structure are those ofsimple metals such as Fe, Cr, Mo, W, Ta, Zr, Nb, V and the like, orthose of alloys thereof, as in the first embodiment.

In the plating treatment for forming the slide surface construction 9,the conditions for the plating bath in carrying out an electrolytic Feplating are as shown in Table 25.

                  TABLE 25    ______________________________________    Plating bath    Ferrous sulfate    (g/liter)       pH     Temperature (°C.)    ______________________________________    100-400         3-7    40-70    ______________________________________

The adjustment of pH is carried out using ammonia water.

A pulse current process is mainly utilized as an energizing method, asshown in FIG. 9, as in the first embodiment. In the pulse currentprocess, if an energization time from the start of increasing to thestart of dropping of an electric current I is represented by T_(ON), anda cycle time is represented by T_(C), wherein one cycle is defined asbeing from the start of proceeding increasing to the start of succeedingincreasing, the ratio of the energization time T_(ON) to the cycle timeT_(C), i.e., the time ratio Y_(ON) /T_(C) is set in a range of T_(ON)/T_(C) ≦0.45. The maximum cathode current density CDmax is set in arange of CDmax≧0.22 A/dm², and the average cathode density CDm is set ina range of 0.1 A/dm² ≦CDm≦10 A/dm².

If such a pulse current process is utilized, the ion concentration inthe vicinity of a cathode is uniformized due to the fact that themaximum electric current alternately flows and does not flow in theplating bath. Thus, the composition of the slide surface constructioncan be stabilized.

In the above-described electrolytic Fe plating process, theprecipitation and content of the (hhh) oriented Fe crystals or the(2hhh) oriented Fe crystals and the like are controlled by changing theplating bath conditions and the energizing conditions. This control iseasy under the utilization of the pulse current process and hence, theslide surface 12 is easily formed into an intended form.

In addition to the electrolytic Fe plating, other examples of a platingprocess are a PVD process, a CVD process, a sputtering process, an ionplating and the like, which are gas-phase plating processes. Theconditions for carrying out a W or Mo plating by the sputtering processwere as follows: For example, the Ar gas pressure was 0.2 to 1 Pa; theaverage Ar gas accelerating electric power was D.C. 1 to 2.5 kW; and thesubstrate temperature was 150 to 450° C. The conditions for carrying outa W plating by the CVD process were as follows: For example, thestarting material was WF6; the flow rate of a gas was 2 to 15 cc/min;the pressure in a chamber was 50 to 300 Pa; the substrate temperaturewas 400 to 650° C.; and the average output of ArF excimer laser was 5 to60 W.

A specified example will be described below.

For simulating of a cylinder sleeve 36, as shown in FIG. 44, a slidesurface construction 9 formed of an aggregate of Fe crystals and havinga thickness of 15 μm was formed by subjecting an outer peripheralsurface of a round bar 46 made of cast iron (JIS FC250) and having adiameter of 6.5 mm to an electrolytic Fe plating process.

Table 26 shows the conditions for the electrolytic Fe plating processfor examples 1 to 8 of the slide surface construction. The plating timewas varied within 5 to 60 minutes in order to set the thickness of theexamples 1 to 8 at 15 μm, as described above.

                                      TABLE 26    __________________________________________________________________________    Plating bath    Slide Ferrous      Pulse current process    surface          sulfate                 Temperature                       CDmax    construction          (g/liter)              pH (° C.)                       (A/dm.sup.2)                           CDm (A/dm.sup.2)                                  T.sub.ON /T.sub.C                                      T.sub.ON (msec)    __________________________________________________________________________    Example 1          400 6.5                 65    40  8      0.2 2    Example 2          350 6.3                 60    27.5                           5.5    0.2 2    Example 3          300 6  60    20  4      0.2 2    Example 4          400 6  50    20  4      0.2 2    Example 5          300 6  50    15  3      0.2 2    Example 6          250 5.5                 50    15  3      0.2 2    Example 7          200 4.5                 50    17.5                           3.5    0.2 2    Example 8          200 3  50    2.5 0.5    0.2 2    __________________________________________________________________________

Table 27 shows the crystal form of the slide surface, the content A andgrain size of the rounded and/or angular hexagonal pyramid-shaped Fecrystals in the slide surface, the content S of the oriented Fecrystals, and the hardness of a section of the slide surfaceconstruction for the examples 1 to 8.

                                      TABLE 27    __________________________________________________________________________                  Rounded and angular                  hexagonal pyramid-    Slide Crystal form                  shaped Fe crystals                            Content S (%) of oriented Fe    surface          of slide                  Area rate                       Grain                            crystals    construction          surface A (%)                       size (μm)                            {110}                                {200}                                    {211}                                        {310}                                            {222}                                                Hardness HmV    __________________________________________________________________________    Example 1          Rounded 100  2    0   0   1.9 0   98.1                                                435          hexagonal          pyramid-shaped    Example 2          Rounded 70   2.3  5.4 2.9 16.1                                        2.1 73.5                                                401          hexagonal          pyramid-shaped          and granular    Example 3          Rounded 40   1.7  21.9                                3.6 31.1                                        2.6 40.8                                                356          hexagonal          pyramid-shaped          and granular    Example 4          Angular 100  1.8  0   0   3.5 0   96.5                                                410          hexagonal          pyramid-shaped    Example 5          Angular 70   1.8  6   3.9 17.6                                        2.6 69.9                                                392          hexagonal          pyramid-shaped          and granular    Example 6          Angular 40   2    21.8                                3.5 30.8                                        2.4 41.5                                                352          hexagonal          pyramid-shaped          and granular    Example 7          Angular 35   1.7  19.4                                12.4                                    19.7                                        13  35.5                                                246          hexagonal          pyramid-shaped          and granular    Example 8          Granular                  0    --   33.6                                16.5                                    17.5                                        17.7                                            14.7                                                210    __________________________________________________________________________

The area rate A of the rounded and angular hexagonal pyramid-shaped Fecrystals was determined according to an equation, A=(c/b×100(%), whereinb represents an area of the slide surface, and c represents an areaoccupied by all the rounded and angular hexagonal pyramid-shaped Fecrystals in the slide surface. The grain size of the rounded and angularhexagonal pyramid-shaped Fe crystals is an average value of distancesbetween opposed corners on the opposite sides of an apex, i.e., oflengths of three diagonal lines.

The content S of the oriented Fe crystals was determined in the samemanner as in the first embodiment, based on the X-ray diffractionpatterns (X-ray was applied in a direction perpendicular to the slidesurface) for the examples 1 to 8. FIG. 45 is the X-ray diffractionpattern for the example 1, FIG. 46 is the X-ray diffraction pattern forthe example 4, and FIG. 47 is the X-ray diffraction pattern for theexample 8.

FIG. 48A is a photomicrograph of the example 1, FIG. 48B is an enlargedphotomicrograph taken from FIG. 48A, and FIG. 48C is an enlargedphotomicrograph taken from FIG. 48B. In these photomicrographs, a largenumber of rounded hexagonal pyramid-shaped Fe crystals are observed. Inthis case, the area rate A of the rounded hexagonal pyramid-shaped Fecrystals is equal to 100%, as shown in Table 27. Each of the roundedhexagonal pyramid-shaped Fe crystals is a {222} oriented Fe crystal withits (hhh) plane, i.e., {222} plane oriented toward the slide surface.The content S of the {222} oriented Fe crystals is equal to 98.1%, asshown in Table 27 and FIG. 45. The area rate A was calculated for therounded hexagonal pyramid-shaped Fe crystals, including pyramid-shapedFe crystals which were incompletely grown to have five ridgelines, asshown in FIG. 48B, but supposed to be completely grown to have sixridgelines.

FIG. 49 is a photomicrograph showing the crystal form of the slidesurface in the example 3, wherein a plurality of rounded hexagonalpyramid-shaped Fe crystals are observed. In this case, the area rate Aof the rounded hexagonal pyramid-shaped Fe crystals is equal to 40%, asshown in Table 27. This area rate A was calculated in the same manner asin the example 1.

FIG. 50 is a photomicrograph showing the crystal form of the slidesurface in the example 4, wherein a large number of angular hexagonalpyramid-shaped Fe crystals are observed. In this case, the area rate Aof the angular hexagonal pyramid-shaped Fe crystals is equal to 100%, asshown in Table 27. Each of the angular hexagonal pyramid-shaped Fecrystals is a {222} oriented Fe crystal with its (hhh) plane, i.e.,{222} plane oriented toward the slide surface. The content S of the{222} oriented Fe crystals is equal to 96.5%, as shown in FIG. 44.

If the example 1 is compared with the example 4; the example 2 iscompared with the example 5, and the example 3 is compared with theexample 6 in Tables 26 and 27, the pH and temperature as well as eventhe concentration of ferrous sulfate of the plating bath for theexamples 1, 2 and 3 tend to be high, as compared with those for theexamples 4, 5 and 6. It is believed that the rounded hexagonalpyramid-shaped Fe crystals are precipitated in the examples 1, 2 and 3due to the above fact.

If the example 1 shown in FIG. 48C is compared with the example 3 shownin FIG. 49, the valley bottom in the V groove-like region in the example1 is arcuate, but the valley bottom in the V groove-like region in theexample 3 is near rectilinear. As a result, the depth of the Vgroove-like region in the example 1 is shallower than that in theexample 3. This is attributable to the fact that the example 1 is highin maximum cathode current density CDmax and average cathode currentdensity CDm and also high in pH, as compared with the example 3.

FIG. 51 is photomicrograph showing the crystal form of the slide surfacein the example 8, wherein a large number of granular Fe crystals areobserved.

Then, the dynamic friction coefficient μ for the examples 1 to 8 wasmeasured using a Fabry friction tester by a method which will bedescribed below.

First, in order to reproduce an oil having a high viscosity at a lowertemperature, an oil corresponding to 10W-30 (in SAE viscosityclassification) and PAMA (polyalkyl methacrylate) were mixed in aproportion of 71:29 (calculated according to JIS K2283) by volumepercentage (%) to prepare an oil mixture having a dynamic viscosity of364 cSt. The dynamic viscosity of the oil corresponding to 10W-30 atambient temperature was 90 cSt, and that of the PAMA was 128500 cSt.

As shown in FIG. 52, a portion of the round bar 46 having a slidesurface construction 9 formed thereon was clamped by a pair of V-blocks50 made of a steel (JIS SCM420, a carburized material) and immersed inthe oil mixture. The round bar 46 was rotated at 300 rpm in the oilmixture, and a test load of 3.6 N was applied to the round bar 46 byboth the V blocks 47. After a lapse of 2 minutes from the time when theload on the round bar 46 reached the test load, the dynamic frictioncoefficient μ was measured. Results are given in Table 28.

                  TABLE 28    ______________________________________    Slide surface construction                    Dynamic friction coefficient μ    ______________________________________    Example 1       0.166    Example 2       0.186    Example 3       0.267    Example 4       0.236    Example 5       0.243    Example 6       0.315    Example 7       0.469    Example 8       0.472    ______________________________________

FIG. 53 shows the relationship between the area rate A of the roundedand angular hexagonal pyramid-shaped Fe crystals and the dynamicfriction coefficient μ. As is apparent from FIG. 53, if the area rate Aof the rounded and angular hexagonal pyramid-shaped Fe crystals is setin a range of A≧40% as in the examples 1 to 3 and 4 to 6, it can be seenthat the dynamic friction coefficient μ is remarkably reduced. This isbecause the solid contact is avoided by an oil retention enhancingeffect provided by the rounded and angular hexagonal pyramid-shaped Fecrystals.

If the examples 1 to 3 and the examples 4 to 6 having the same area rateA of the rounded and angular hexagonal pyramid-shaped Fe crystals in therange of A≧40% are compared with each other (the example 1 with theexample 4; the example 2 with the example 5; and the example 3 with theexample 6), it can be also seen that the dynamic friction coefficient μof the examples 1 to 3 having the rounded hexagonal pyramid-shaped Fecrystals in the slide surface is lower than those of the examples 4 to 6having the angular hexagonal pyramid-shaped Fe crystals by about 15 toabout 30%. This is attributable to the fact the flow of the oil mixtureof the high viscosity in the examples 1 to 3 is smooth, as compared withthat in the examples 4 to 6.

Therefore, by providing the examples 1 to 3, particularly the examples 1and 2 on the inner peripheral surface of the cylinder sleeve, thefriction loss can be reduced, even when the viscosity of the oil is highat a low temperature and the like.

Then, examples 1 to 8 of slide surface constructions were formed on anouter periphery of one surface of a disk made of a cast iron (JIS FC250)in the same manner as that described above and subjected to a seizuretest in a chip-on-disk manner under lubrication to measure the seizuregenerating load, thereby providing the results given in Table 29.Conditions for the seizure test were as follows: the material for thechip was an aluminum alloy (JIS AC8A, T7-treated material); theperipheral speed of the disk was 15 m/sec; an oil corresponding to10W-30 at room temperature was used; the amount of oil supplied was 40ml/min; the area of the slide surface of the chip was 1 cm² ; the methodfor applying load to the chip was to first apply a load of 20 N andmaintain it for 2 minutes and after that, the load was increased insequence by 20 N while maintaining it each time the load was increased.

                  TABLE 29    ______________________________________    Slide surface construction                     Seizure generating load (N)    ______________________________________    Example 1        1480    Example 2        1170    Example 3        820    Example 4        1450    Example 5        1150    Example 6        850    Example 7        330    Example 8        280    ______________________________________

FIG. 54 is a graph taken from Table 29. As is apparent from FIG. 54, theseizure generating loads for the examples 1 to 3 are substantially equalto those in the examples 4 to 6, respectively, when the area rate A isin the range of A≧40%. From this, it was made clear that even if therounded hexagonal pyramid-shaped Fe crystals exist in the slide surface,a seizure resistance equivalent to that provided when the angularhexagonal pyramid-shaped Fe crystals exist in the slide surface, can beobtained.

The third embodiment is not limited to the cylinder sleeve and isapplicable to various slide members such as a piston, a cam shaft, apiston ring, a cylinder sleeve and the like.

FOURTH EMBODIMENT

Referring to FIG. 55, a piston 19 for an internal combustion engineincludes a piston body 19a made of an aluminum alloy. A lamellar slidesurface construction 9 is formed on outer peripheral surfaces of a landportion 20 and a skirt portion 21 of the piston body 19a by plating.

The slide surface construction 9 is formed of an aggregate of metalcrystals having a body-centered cubic structure (which will be alsoreferred to as a bcc structure hereinafter), as shown in FIG. 5. Theaggregate includes a plurality of columnar crystals 28 grown from thepiston body 19a, as shown in FIG. 56. Each of the columnar crystals 28is a (hhh) oriented metal crystal with its (hhh) plane (by Millerindices) oriented toward a slide surface. As also shown in FIG. 57, eachof the tip ends of the columnar crystals is in the form of a truncatedhexagonal pyramid-shaped metal crystal (truncated pyramid-shapedprojection) 48 in the slide surface 12. The area rate A of the truncatedhexagonal pyramid-shaped metal crystals 48 in the slide surface is setin a range of 40%≦A≦100%.

As clearly shown in FIG. 58A, a top face of the truncated hexagonalpyramid-shaped metal crystal 48 is formed of a plurality of flat faceportions 49a, 49b, 49c, 49d, 49e and 49f. Steps "s" are provided betweenadjacent flat face portions 49a and 49b; 49b and 49c; 49c and 49d; 49dand 49e; 49e and 49f; and 49f and 49a, respectively, as shown in FIG.58B.

In the illustrated embodiment, the top face 49 is divided into the sixflat face portions 49a to 49f by three dividing lines L₃, L₄ and L₅which interconnect three sets of two opposed sides to bisect the opposedsides and which extend through an inner center o. The flat face portions49a to 49f comprise three protruding flat face portions 49a, 49c and 49eand three depressed flat face portions 49b, 49d and 49f, which arealternately located about the inner center o. In this case, the step "s"is of about 0.1 to about 0.5 μm.

If the area rate A of the truncated hexagonal pyramid-shaped metalcrystals 48 in the slide surface 12 is set in the above-described range,the adjacent ones of the truncated hexagonal pyramid-shaped metalcrystals 48 assume mutually biting states, as shown in FIG. 57. Thus,the slide surface takes on a very intricate aspect comprising a largenumber of extremely fine crests 31, a large number of complicated andextremely fine valleys 32 formed between the crests 31 and extending atrandom, and a large number of extremely fine swamps 33 formed due to themutual biting of the crests 31. Moreover, the intricateness is doubledby the fact that the top face 49 of the truncated hexagonalpyramid-shaped metal crystal 48 is formed of the six flat face portions49a to 49f and the steps "s" are provided between the adjacent flat faceportions 49a and 49b to 49f and 49a. As a result, the flow resistance ofthe oil on the slide surface 12 is remarkably increased.

Thus, it is possible to remarkably enhance the oil retention of theslide surface construction and hence, even in a severe slidingenvironment, the solid contact can be reduced to the utmost, causing theslide surface construction 9 to exhibit an excellent seizure resistance.In addition, because the top face 49 has the flat face portions 49a to49f, the friction coefficient μ can be reduced, causing the slidesurface construction to exhibit an excellent wear resistance in thesevere sliding environment.

As shown in FIG. 8, the inclination of the (hhh) plane with respect tothe phantom plane 18 along the slide surface 12 appears as theinclination of the truncated hexagonal pyramid-shaped metal crystals 48and hence, an influence is imparted to the oil retention of the slidesurface construction. The inclination angle θ formed by the (hhh) planewith respect to the phantom plane 18 is set in a range of 0°≦θ≦15° as inthe first embodiment. In this case, the direction of inclination of the(hhh) plane is not limited. If the inclination angle θ is larger than15°, the oil retention and the wear resistance of the slide surfaceconstruction 9 are reduced.

Examples of the metal crystals having the bcc structure are those ofsimple metals such as Fe, Cr, Mo, W, Ta, Zr, Nb, V and the like, orthose of alloys thereof, as in the first embodiment.

In producing the slide surface construction 9, the following steps areemployed: a step for forming a deposit layer 50 including a plurality ofhexagonal pyramid-shaped metal crystals 16 in a surface which becomes aslide surface 12 with an area rate A of the hexagonal pyramid-shapedmetal crystals 16 in the surface being in a range of 40%≦A≦100%, onouter peripheral surfaces of the land portion 20 and the skirt portion21 of the piston body 19a by plating, as shown in FIGS. 59 and 60; astep for subjecting the surface of the deposit layer 50 to a polishingto form the hexagonal pyramid-shaped metal crystals 16 into truncatedhexagonal pyramid-shaped metal crystals 48 each having a top face, asshown in FIG. 61; and a step for subjecting the polished surface of thedeposit layer 50 to an etching treatment to divide the top face of thetruncated hexagonal pyramid-shaped metal crystal 48 into six flat faceportions 49a to 49f and to provide steps "s" between the adjacent flatface portions 49a and 49b to 49f and 49a, as shown in FIGS. 56 to 58B.

In the plating treatment for forming the deposit layer 50, conditionsfor a plating bath in carrying out an electrolytic Fe plating processare as given in Table 30.

                  TABLE 30    ______________________________________    Plating bath    Ferrous sulfate    (g/liter)       pH     Temperature (°C.)    ______________________________________    100-400         3-6.8  10-60    ______________________________________

A pulse current process is mainly utilized as an energizing method, asshown in FIG. 9, as in the first embodiment. In the pulse currentprocess, the ratio of the energization time T_(ON) to the cycle timeT_(C), i.e., the time ratio T_(ON) /T_(C) is set in a range of T_(ON)/T_(C) ≦0.45. The maximum cathode current density CDmax is set in arange of CDmax≧2 A/dm², and the average cathode current density CDm isset in a range of 1 A/dm² ≦CDm≦10 A/dm².

If such a pulse current process is utilized, the ion concentration inthe vicinity of a cathode is uniformized due to the fact that themaximum electric current alternately flows and does not flow in theplating bath. Thus, the composition of the slide surface constructioncan be stabilized.

In the above-described electrolytic Fe plating process, theprecipitation and content of the (hhh) oriented Fe crystals, i.e., Fecrystals with their tip ends being in the form of hexagonalpyramid-shaped Fe crystals 16 and the like are controlled by changingthe plating bath conditions and the energizing conditions.

In addition to the electrolytic Fe plating, other examples of a platingprocess are a PVD process, a CVD process, a sputtering process, an ionplating and the like, which are gas-phase plating processes. Conditionsfor carrying out a W or Mo plating by the sputtering process were asfollows: For example, the Ar gas pressure was 0.2 to 1 Pa; the averageAr gas accelerating electric power was D.C. 1 to 1.5 kW; and thesubstrate temperature was 150 to 300° C. Conditions for carrying out a Wplating by the CVD process were as follows: For example, the startingmaterial was WF₆ ; the flow rate of a gas was 2 to 15 cc/min; thepressure in a chamber was 50 to 300 Pa; the substrate temperature was400 to 600° C.; and the average output of ArF excimer laser was 5 to 40W.

A diamond wheel is used for the polishing, and the grain size of adiamond abrasive grain is of about 0.25 μm.

The etching treatment is carried out at room temperature. An alcoholsolution containing 3 to 5% of nitric acid is used as an etchingsolution for the Fe deposit layer, and the immersion time is set in arange of 30 to 60 seconds. An aqueous solution containing 10% of sodiumhydroxide and 10% of sodium ferricyanide is used as an etching solutionfor the Mo and W deposit layers, and the immersion time is set in arange of 15 to 60 seconds.

A specified example will be described below.

A deposit layer 50 formed of an aggregate of Fe crystals and having athickness of 15 μm was formed by subjecting outer peripheral surfaces ofa land portion 20 and a skirt portion 21 of a piston body 19a made of analuminum alloy (JIS AC8B-T7) to an electrolytic Fe plating process.

Table 31 shows the conditions for the electrolytic Fe plating processfor examples 1a to 6a of the deposit layers. The plating time was variedwithin a range of 10 to 60 minutes in order to set the thickness of theexamples 1a to 6a at 15μ, as described above.

                                      TABLE 31    __________________________________________________________________________           Plating bath           Ferrous       Pulse current process    Deposit           sulfate Temperature                         CDmax                              CDm      T.sub.ON    Layer  (g/liter)               pH  (° C.)                         (A/dm.sup.2)                              (A/dm.sup.2)                                  T.sub.ON /T.sub.C                                       (msec)    __________________________________________________________________________    Example 1b           400 6.5 45    20   4   0.2  2    Example 2b           400 6.5 42    20   4   0.2  2    Example 3b           400 6.5 42    10   3   0.3  2    Example 4b           400 6.5 42    10   3   0.3  2    Example 5b           400 6.5 42    7    2   0.3  2    Example 6b           400 6   50    8    4   0.5  2    __________________________________________________________________________

Table 32 shows the crystal form of the deposit layer surface, the arearate A and grain size of the hexagonal pyramid-shaped Fe crystals in thedeposit layer surface, the content of the oriented Fe crystals, and thehardness of a section of the deposit layer.

                                      TABLE 32    __________________________________________________________________________                Hexagonal pyramid-    Crystal     shaped Fe crystals                          Content S (%) of Hexagonal                                              Hard-    Deposit          form of                Area rate                     Grain                          pyramid-shaped Fe crystals                                              ness    layer surface                A (%) size                     (μm)                          {110}                              {200}                                  {211}                                      {310}                                          {222}                                              HmV    __________________________________________________________________________    Example 1a          Hexagonal                90   5-10 2.8 1.7 3.3 1.1 91.1                                              430          pyramid-          shaped    Example 2a          Hexagonal                80   5-10 5.4 1.8 7.2 1.1 84.5                                              450          pyramid-          shaped    Example 3a          Hexagonal                60   5-10 17.4                              2.3 15.5                                      2.7 62.1                                              400          pyramid-          shaped and          block-like    Example 4a          Hexagonal                40   5-10 18.4                              8.6 17.9                                      9.5 45.6                                              370          pyramid-          shaped and          block-like    Example 5a          Hexagonal                30   5-10 20.1                              9   19.9                                      12.6                                          38.4                                              320          pyramid-          shaped and          block-like    Example 6a          Granular                0    --   18.6                              20.4                                  17.2                                      21.5                                          22.3                                              250    __________________________________________________________________________

The area rate A of the hexagonal pyramid-shaped Fe crystals wasdetermined according to an equation, A=(c/b)×100(%), as in the secondembodiment, wherein b represents an area of the deposit layer surface,and c represents an area occupied by all the hexagonal pyramid-shaped Fecrystals in the surface. The grain size of the hexagonal pyramid-shapedFe crystals is an average value of distances between opposed corners onthe opposite sides of an apex, i.e., of lengths of three diagonal lines.

The content S was determined in the same manner as in the firstembodiment, based on the X-ray diffraction patterns (X-ray was appliedin a direction perpendicular to the deposit layer surface) for theexamples 1a to 6a. FIG. 62 is the X-ray diffraction pattern for theexample 1a.

FIG. 63 is a photomicrograph showing the crystal form of the surface inthe example 1a, wherein a large number of hexagonal pyramid-shaped Fecrystals are observed. In this case, the area rate A of the hexagonalpyramid-shaped Fe crystals is equal to 90%, as shown in Table 32. Eachof the hexagonal pyramid-shaped Fe crystals is a {222} oriented Fecrystal with its (hhh) plane, i.e., {222} plane oriented toward thesurface. The content S of the {222} oriented Fe crystals is equal to91.1%, as shown in Table 32 and FIG. 62.

FIG. 64 is a photomicrograph showing the crystal form of the surface inthe example 3a, wherein a large number of hexagonal pyramid-shaped Fecrystals and a large number of block-like Fe crystals are observed.

Then, each of the surfaces of the examples 1a to 5a of the depositlayers was subjected to a polishing by a diamond wheel to form thehexagonal pyramid-shaped Fe crystals into truncated hexagonalpyramid-shaped Fe crystals, thereby providing examples 1b to 5bcorresponding to the examples 1a to 5a, respectively. FIG. 65 is aphotomicrograph showing the crystal form of the surface in the example1b, wherein a top face of the truncated hexagonal pyramid-shaped Fecrystal is observed.

Thereafter, each of the examples 1b to 5b was subjected to an etchingtreatment, in which it was immersed for 30 seconds in an alcoholsolution containing 5% of nitric acid at ambient temperature, therebyproviding examples 1 to 5 of slide surface constructions correspondingto the examples 1b to 5b, respectively.

FIG. 66A is a photomicrograph showing the crystal form of a slidesurface in the example 1, and FIG. 66B is a tracing of FIG. 66A. It isobserved in FIGS. 66A and 66B that a top face of the truncated hexagonalpyramid-shaped Fe crystal 48 is comprised of six flat face portions 49a,49b, 49c, 49d, 49e and 49f, so that the three protruding flat faceportions 49a, 49c and 49e and the depressed flat face portions 49b, 49dand 49f are alternately located about an inner center o.

The reason why the protruding flat face portions and the depressed flatface portions appear on the top face is presumed as being in that thecrystal defining one of the flat face portions and the crystal definingthe other flat face portion form a twin crystal.

The step "s" was measured by vertically cutting the truncated hexagonalpyramid-shaped Fe crystal on a diagonal line L by use of a focus ionbeam (FIM), as shown in FIG. 66B and then measuring the step "s" by useof a scanning electronic microscope (SEM). Thus, it was ascertained thatthe step "s" in the examples 1 to 5 was in a range of about 0.1 μm toabout 0.5 μm.

Then, chips having the construction of examples 1 to 5, chips having theconstruction of examples 1b, 2b, 4b and 5b after being subjected to thepolishing, and chips having the construction of example 6a of thedeposit layer, were fabricated and subjected to a seizure test in achip-on-disk manner under lubrication to measure the seizure generatingload, thereby providing the results given in Table 33. The condition forthe seizure test were as follows: the material for a disk was a castiron (JIS FC250), the peripheral speed of the disk was 15 m/sec; theamount of oil supplied was 40 ml/min; the area of the slide surface ofthe chip was 10 mm² ; and the load on the chip was increased at a rateof 50 N/min.

                  TABLE 33    ______________________________________                          Seizure generating load (N)    ______________________________________    Slide surface                Example 1 2100    construction                Example 2 2000                Example 3 1800                Example 4 1600                Example 5 500    After polishing                Example 1b                          1550                Example 2b                          1500                Example 4b                          1200                Example 5b                          500    Deposit layer                Example 6a                          300    ______________________________________

FIG. 67 shows the relationship between the area rate A of the truncatedhexagonal pyramid-shaped Fe crystals and the seizure generating load forthe examples 1 to 5, 1b, 2b, 4b, 5b and 6a. It can be seen from FIG. 67that if the area rate A of the truncated hexagonal pyramid-shaped Fecrystals is set in a range of A≧40% and the top face of the truncatedhexagonal pyramid-shaped Fe crystal is comprised of six flat faceportions having steps as described above, the slide surface constructionexhibits an excellent seizure resistance, as shown by examples 1 to 4.

The examples 1b, 2b and 4b are inferior in seizure resistance to theexamples 1, 2 and 4 due to the different structure of the top face. Theexample 5 and 5b are extremely low in seizure resistance due to the factthat the area rate of the truncated hexagonal pyramid-shaped Fe crystalsis lower than 40%, and the example 6a is extremely low in seizureresistance due to the fact that the slide surface is formed of granularFe crystals.

Then, the sliding test was carried out in the same chip-on-disk manneras that described above to measure the dynamic friction coefficient μ atthe time when each of the examples 1 to 5, 1b, 2b, 4b, 5b and 6agenerated a seizure, thereby providing the results given in Table 34.

                  TABLE 34    ______________________________________                            Dynamic friction                            coefficient μ    ______________________________________    Slide surface Example 1 0.008    construction  Example 2 0.008                  Example 3 0.0085                  Example 4 0.0085                  Example 5 0.011    After polishing                  Example 1b                            0.009                  Example 2b                            0.009                  Example 4b                            0.01                  Example 5b                            0.011    Deposit layer Example 6a                            0.014    ______________________________________

FIG. 68 shows the relationship between the area rate A of the truncatedhexagonal pyramid-shaped Fe crystals and the dynamic frictioncoefficient μ for the examples 1 to 5, 1b, 2b, 4b, 5b and 6a. It can beseen in FIG. 68 that if the area rate A of the truncated hexagonalpyramid-shaped Fe crystals is set in a range of A≧40% and the top faceof the truncated hexagonal pyramid-shaped Fe crystal is comprised of thesix flat face portions having steps, the dynamic friction coefficient μcan be remarkably reduced, as in the examples 1 to 4.

The examples 1b, 2b and 4b are higher in dynamic friction coefficient μ,as compared with the examples 1, 2 and 4, due to the different structureof the top face. In the examples 5 and 5b, the dynamic frictioncoefficient μ is increased due to the area rate of the truncatedhexagonal pyramid-shaped Fe crystals being lower than 40%, and in theexample 6a, the dynamic friction coefficient μ is remarkably high due tothe fact that the slide surface is formed of granular Fe crystals.

The fourth embodiment is not limited to the piston for the internalcombustion engine, and is applicable to various slide members such as apiston pin, a cam shaft, a piston ring, a balancer shaft and the like.

What is claimed is:
 1. A slide surface construction formed of anaggregate of Fe crystals including rounded pyramid-shaped Fe crystals,wherein the area rate A of rounded pyramid-shaped Fe crystals in a slidesurface is in a range of 40%≦A≦100%, each of the rounded pyramid-shapedFe crystals having a plurality of ridgelines, each ridgeline having aconvex arcuate shape, a slope-correspondence area being defined betweenadjacent ones of said ridgelines and comprising two band-like regionsand a V groove-like region connected between said two band-like regions,wherein each said band-like region is one slope of two slopes formingeach said ridgeline, and wherein said V groove-like region has anopening width that gradually reduces from a skirt portion toward an apexof said rounded pyramid-shaped metal crystal.
 2. A slide surfaceconstruction according to claim 1, wherein said V groove-like region hasa valley bottom which assumes a convex arcuate shape to follow saidridgeline.
 3. A slide surface construction according to claim 1 or 2,wherein each of said Fe crystals has a body-centered cubic structure,and said rounded pyramid-shaped Fe crystals are at least one of (hhh)oriented Fe crystals with their (hhh) planes (by Miller indices)oriented toward the slide surface, and (2hhh) oriented Fe crystals withtheir (2hhh) planes (by Miller indices) oriented toward the slidesurface.
 4. A slide surface construction according to claim 1 or 2,wherein each of said rounded pyramid-shaped Fe crystals is a (hhh)oriented Fe crystal whose (hhh) plane (by Miller indices) is orientedtoward the slide surface and which is hexagonal pyramid-shaped.
 5. Aslide surface construction according to claim 3, wherein each of saidrounded pyramid-shaped Fe crystals is a (hhh) oriented Fe crystal whose(hhh) plane (by Miller indices) is oriented toward the slide surface andwhich is hexagonal pyramid-shaped.
 6. A slide surface constructionaccording to claim 1 or 2, wherein each of said rounded pyramid-shapedFe crystals has an inclination angle Θ formed by the (hhh) plane withrespect to a phantom plane of 0°≦Θ≦15°.
 7. A slide surface constructionaccording to claim 1 or 2, wherein said slide surface construction isformed by a plating treatment.
 8. A slide surface construction accordingto claim 1 or 2, wherein said slide surface construction is formed byone plating process among an electrolytic plating, a PVD platingprocess, a CVD plating process, a sputtering process and an ion plating.